Semiconductor wafer drying apparatus

Abstract

Disclosed is a semiconductor wafer drying apparatus for rapidly evaporating liquid present between fine patterns on the surface of a semiconductor wafer. The apparatus includes: a support device for supporting a semiconductor wafer; a laser beam-generating device for generating a laser beam; a line beam-forming device for forming the laser beam generated from the laser beam-generating device into a line beam having a length greater than the diameter of the semiconductor wafer, and irradiating the semiconductor wafer with the generated line beam; and a moving device for moving the line beam or the semiconductor wafer to allow the line beam to scan the entire surface of the semiconductor wafer.

Description

Semiconductor wafer drying device

[0001] The present invention relates to a semiconductor wafer drying device, and more particularly, to a semiconductor wafer drying device that effectively evaporates and dries a liquid such as ultrapure water or IPA remaining on a semiconductor wafer after a semiconductor wafer cleaning process without damaging the micro-pattern on the surface of the semiconductor wafer.

[0002] Patterns currently implemented on semiconductor wafers consist of ultra-fine structures measuring 10 nm or less. These microscopic patterns are used in structures such as DRAM capacitors and logic device transistors, and they have extremely high aspect ratios.

[0003] Figure 1 shows a cross-section of a semiconductor micropattern.

[0004] Referring to Fig. 1, a fine pattern with a small pattern spacing (d) is obtained through an etching process, and then a chemical wet cleaning process is performed to remove residues and foreign substances remaining around the fine pattern. After the wet cleaning process, a rinse process using ultrapure water is necessarily performed. Afterwards, a drying process is performed while rotating the wafer at high speed. During the rinse process, ultrapure water is filled between the fine patterns, and during the drying process, the fine patterns are bent by the capillary force (σ) of the ultrapure water filled between the fine patterns. This is called the pattern leaning phenomenon, and as the pattern size decreases, a serious pattern damage problem occurs.

[0005] To minimize the capillary forces that cause micropattern warping, a technology exists that involves spraying isopropyl alcohol (IPA), which has a low surface tension (γ), onto the wafer after the ultrapure water process. This process then replaces the ultrapure water within the pattern with isopropyl alcohol, thereby drying the wafer. This technique replaces the liquid between the patterns with isopropyl alcohol, which has a low surface tension, thereby reducing capillary forces and thus pattern leaning.

[0006] However, in recent ultra-fine pattern processes below 10 nm, even the alcohol substitution method mentioned above cannot prevent pattern lining. Therefore, a drying method using a CO2 supercritical fluid has been recently introduced. A supercritical fluid is a substance that has exceeded its critical pressure and critical temperature, and at this time, its surface tension is close to 0 like a gas, so it can penetrate any fine pattern and perform a drying process without damaging the pattern. In the case of the representatively used CO2 supercritical, the critical temperature is 31.1 ° C and the critical pressure is 73.8 Bar, requiring an extremely high-pressure device.

[0007] However, the ultra-high pressure CO2 supercritical fluid drying device described above is very expensive, has significant safety issues, requires a high drying cost per wafer, and has the disadvantage of being impossible to integrate into existing wet cleaning equipment.

[0008] Accordingly, in the field of technology, there is a need for a technology that can suppress the occurrence of pattern lining, in which (ultra)fine patterns formed on a semiconductor wafer are warped, even when rinsing the semiconductor wafer with a liquid such as ISP or ultrapure water rather than a supercritical fluid.

[0009] The present invention has been made to solve the problems of the prior art, and provides a semiconductor wafer drying device that can effectively dry a semiconductor wafer by creating a line beam of a size covering the diameter (or maximum width) of a semiconductor wafer and scanning the line beam over the entire exposed surface of the semiconductor wafer, thereby very quickly evaporating a liquid such as ultrapure water or IPA remaining in a fine pattern, thereby suppressing damage to the fine pattern due to the surface tension of the liquid.

[0010] According to one aspect of the present invention, a semiconductor wafer drying device for rapidly evaporating a liquid existing between micro-patterns on a semiconductor wafer surface is provided, the semiconductor wafer drying device including: a support device for supporting a semiconductor wafer; a laser beam generating device for generating a laser beam; a line beam forming device for forming a laser beam generated from the laser beam generating device into a line beam having a length greater than a diameter of the semiconductor wafer and irradiating the line beam onto the semiconductor wafer; and a moving device for moving the line beam or the semiconductor wafer so that the line beam can scan the entire semiconductor wafer.

[0011] The above laser beam generating device generates a continuous wave infrared laser beam having a wavelength of 900 nm or more.

[0012] The above line beam forming device includes a polygon mirror that rotates by a motor and continuously reflects a laser beam, and a focusing lens that is positioned between the polygon mirror and a semiconductor wafer and cooperates with the polygon mirror to form a line beam.

[0013] The above polygon mirror includes 6 to 10 facets that reflect the laser beam.

[0014] The above focusing lens may be an F-theta lens or a telecentric lens.

[0015] According to one aspect of the present invention, a semiconductor wafer wet cleaning facility comprises a wafer transfer device for transferring a semiconductor wafer; and a wet cleaning chamber for wet cleaning a semiconductor, the facility including a line beam forming device integrated inside the wafer transfer device or within the wet chamber and forming a laser beam into a line beam to complete wet cleaning within the wet chamber or to irradiate a semiconductor wafer transferred by the wafer transfer device, wherein the line beam forming device includes a polygon mirror that rotates by a motor and continuously reflects a laser beam, and a focus lens that is positioned between the polygon mirror and the semiconductor wafer and cooperates with the polygon mirror to form the laser beam into a line beam.

[0016] The above line beam forming device forms a continuous wave infrared laser beam having a wavelength of 900 nm or more generated from a laser beam generating device into a line beam having a length greater than the diameter of a semiconductor wafer.

[0017] The above wet cleaning equipment further includes a wafer transfer robot including a support device for supporting a semiconductor wafer, and the wafer transfer robot moves a semiconductor wafer to which a line beam is irradiated so that the semiconductor wafer is scanned on a full surface.

[0018] According to the present invention, a continuous wave laser beam of an infrared wavelength is used, a polygon mirror and a focusing lens are used to form a line beam of 300 mm or more, and the line beam is scanned across the entire surface of the wafer, thereby very quickly evaporating a liquid such as ultrapure water or IPA contained in a fine pattern, thereby effectively performing wafer drying without damaging the fine pattern.

[0019] The semiconductor wafer drying device according to the present invention prevents damage, such as pattern leaning, that occurs during conventional drying processes using IPA replacement. Compared to conventional CO2 supercritical fluid drying devices, the device offers significantly lower prices, simpler processes, safer operation, and significantly lower drying costs. Furthermore, its compact modular design allows for easy integration into existing wet cleaning equipment.

[0020] Figure 1 is a drawing to explain the cause of pattern damage that occurs during the semiconductor wafer drying process.

[0021] Figure 2 is a conceptual perspective view for explaining the semiconductor wafer drying device according to the present invention in general.

[0022] Figure 3 is a drawing for conceptually explaining a semiconductor wafer drying device according to the present invention.

[0023] Figure 4 is a drawing explaining polygon mirror scanning by semiconductor wafer drying.

[0024] Figure 5 is a drawing showing a comparative example of general galvano-mirror scanning.

[0025] Figure 6 is a conceptual drawing of a wet cleaning equipment in which a semiconductor wafer drying device according to the present invention is modularized and operated.

[0026] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings so that those skilled in the art can easily implement the invention. The present invention may be implemented in various different forms and is not limited to the embodiments described herein.

[0027] In describing the present invention, the size and shape of components shown in the drawings may be exaggerated or simplified for clarity and convenience of explanation.

[0028] Additionally, terms specifically defined in consideration of the structure and operation of the present invention may vary depending on the intent or custom of the user or operator. These terms should be interpreted with meanings and concepts consistent with the technical spirit of the present invention, based on the contents of this specification.

[0029] In order to clearly explain the present invention, the description of parts unrelated to the technical idea of ​​the present invention is omitted, and the same reference numerals are used for identical or similar components throughout the specification.

[0030] In addition, in various embodiments, components having the same configuration are described only in representative embodiments using the same symbols, and in other embodiments, only configurations different from the representative embodiments are described.

[0031] Throughout the specification, when a part is said to be "connected" to another part, this includes not only "directly connected" but also "indirectly connected" with other elements intervening. Furthermore, when a part is said to "include" a component, this may mean that the other component is included, rather than excluded, unless otherwise specifically stated.

[0032] As illustrated in FIGS. 2 and 3, a semiconductor wafer drying device according to an embodiment of the present invention is a device for very quickly evaporating and drying a liquid remaining between micro-patterns formed on a semiconductor wafer (2), more specifically, micro-patterns formed with an ultra-fine structure of 10 nm or less, more specifically, a liquid such as ultra-pure water or ISP, and includes a support device (10) for supporting a semiconductor wafer (2), a laser beam generating device (20) for generating a laser beam (3) of a specific wavelength, a line beam forming device (30) for forming the laser beam (3) generated from the laser beam generating device (20) into a laser line beam (4) covering the diameter (or width) of the semiconductor wafer (2), and a moving device (40) for moving the support device (10) or the line beam forming device (30) so that the semiconductor wafer (2) is scanned entirely with the laser line beam (4) formed by the line beam forming device (30).

[0033] The above laser beam generating device (20) uses a continuous wave infrared wavelength laser having a wavelength of 900 nm or more. The continuous wave (CW: Continuous Wave) laser beam (3) generated from the laser beam generating device (20) is introduced into a line beam forming device (30). The continuous wave laser beam (3) of the infrared wavelength provides constant infrared energy in the form of a continuous beam.

[0034] The above line beam forming device (30) includes a polygon mirror (32) that rotates by a driving unit including a motor (33), a reflection mirror (31) that reflects a laser beam of a continuous wave infrared wavelength band input from the laser beam generating device (20) onto the polygon mirror (32), and a focusing lens (34) that is positioned between the polygon mirror (31) and a semiconductor wafer (2) and cooperates with the polygon mirror (32) to create a laser line beam (4) of a certain size.

[0035] As mentioned above, the introduced laser beam is irradiated to the polygon mirror (32) rotating at high speed through the reflection mirror (31). The polygon mirror (32) having a polygonal shape reflects the laser beam at a certain angle (θ) on one side, and the reflected laser beam is focused through the focusing lens (34). At this time, the focused laser beam takes the form of a line beam (4). At this time, the size of the laser line beam (4), i.e., the cross-sectional length of the laser line beam (4) at the position where it meets the semiconductor wafer (2), is preferably set to be slightly larger than the diameter (width) of the target semiconductor wafer (2). For example, when the semiconductor wafer to be dried is a semiconductor wafer (2) having a diameter of 300 mm, the size of the laser line beam (4) is preferably 310 mm or more.

[0036] In this embodiment, the moving device (40) moves the supporting device (10) in a direction perpendicular to the laser line beam (4) to move the semiconductor wafer (2) supported on the supporting device (10). By this movement, the laser line beam (4) can be scanned to cover the entire surface of the semiconductor wafer (2). The supporting device (10) may be a chuck, and the moving device (40) may include various linear motion mechanisms.

[0037] A continuous wave (CW) laser beam (3) generated from a laser beam generator (20) is introduced into a line beam forming device (30). The introduced laser beam is irradiated onto a polygon mirror (32) that is rotating at high speed by a high-speed rotation driving unit including a motor (33) through a reflection mirror (31). The polygon mirror (32) having a polygonal shape reflects the laser beam at a constant angle (θ) on one side, and the reflected laser beam is focused through a focusing lens (34). At this time, the focused laser beam takes the form of a line beam (4). As mentioned above, the size of the laser line beam (4) is larger than the diameter of the semiconductor wafer (2) to be dried. The laser line beam (4) formed in this way becomes a very powerful heat source with uniform energy, and by scanning the laser line beam (4) across the entire surface of the semiconductor wafer (2), a drying operation can be performed to very quickly evaporate the liquid inside the micro-pattern provided on the surface of the semiconductor wafer (2).

[0038] In order to perform a drying operation on the entire surface of a semiconductor wafer (2), a laser line beam (4) must be scanned on the entire surface of the semiconductor wafer (2). The moving device (40) may be used in a way that fixes the position of the laser line beam (4) and moves the semiconductor wafer (2) in one direction, or in a way that places the semiconductor wafer (2) in a fixed position and moves the line beam forming device (30) in one direction.

[0039] As mentioned above, the laser beam used in the laser beam generator (20) is a continuous wave infrared laser beam with a wavelength of 900 nm or more. The higher the laser output, the higher the energy density of the line beam (4), enabling rapid drying. It is generally preferable to use an output of 100 W or more.

[0040] The polygon mirror (32) above has a regular polygonal shape with 6 to 10 sides when viewed from the side, and it is preferable to use one with 6 to 10 facets corresponding to each side. If there are many facets, the reflection angle (θ) becomes small, making it difficult to secure a sufficient laser line beam (4) length. If there are few facets, the number of lines formed according to rotation becomes small, making it difficult to obtain a uniform energy distribution. The polygon mirror (32) rotates at high speed by a motor (33) or a driving unit including a motor (33), and at this time, the rotation speed is preferably 5,000 RPM or more. The higher the rotation speed, the more lines are formed, allowing a laser line beam (4) with a more uniform energy distribution to be formed. In addition, high-speed rotation reduces heat accumulation in the polygon mirror (32), thereby preventing heat damage to the mirror.

[0041] The above focusing lens (34) uses an f-theta lens or a telecentric lens to maintain a laser spot of a constant size on the surface of the semiconductor wafer (2). It is preferable to use a telecentric lens to sufficiently secure the uniformity of the incidence angle of the laser beam and the spot size.

[0042] Fig. 4 shows the scanning of a laser line beam (4) on the surface of a wafer (2) according to the present invention. As shown in Fig. 4, the scanning pattern by the polygon mirror (32) inside the line beam forming device (30) can irradiate a laser beam at a dense interval in one direction on the semiconductor wafer (2), thereby performing a uniform drying operation on the entire surface of the semiconductor wafer (2).

[0043] In the case of galvano scanning using a commonly used single mirror (32') presented as a comparative example in Fig. 5, the laser beam moves left and right while scanning, and at this time, a difference occurs in the pitch interval between the center and the periphery, so that uniform laser irradiation cannot be performed on the entire surface of the semiconductor wafer (2), making it difficult to perform a uniform drying operation. In addition, in the case of polygon mirror scanning, high-speed rotation is possible, so the laser beam scanning speed is 100 m / sec or more, and in the case of single mirror galvano scanning, the maximum speed is about 10 m / sec. This has the advantage of being able to perform a uniform drying operation with a very narrow pitch interval in the case of polygon mirror scanning.

[0044] FIG. 6 is a conceptual drawing of a wet cleaning equipment (100) in which all or part of a semiconductor wafer drying device (1) according to the present invention is modularized and applied.

[0045] The laser drying device of the present invention can be modularized and thus easily integrated into existing wet cleaning equipment. When a fiber laser is used as the laser, the laser beam generating device (20; see FIGS. 2 and 3) and the line beam forming device (30) can be connected by an optical fiber. At this time, only the line beam forming device (30) can be easily installed into the existing wet cleaning equipment. As shown in FIG. 6, the line beam forming device (30) of the small modularized laser drying device is installed inside a wafer transfer device (EFEM: Equipment Front End Module) (5), and a semiconductor wafer that has been cleaned using a wafer transfer robot (6) including a semiconductor wafer support device can be placed in a wafer cassette (FOUP: Front Opening Unified Pod; 7) after performing a final drying operation.

[0046] As another example of use, a laser drying device or a line beam forming device (30) belonging thereto may be installed inside each wafer wet cleaning chamber (8) to perform drying immediately after wet cleaning. In this case, if the cleaning time is short and there are many cleaning chambers (8), it is preferable to place it inside the cleaning chamber, and if the cleaning time is long and there are few cleaning chambers, it is preferable to install it inside the wafer transfer device (5). As described above, the line beam forming device (30) may include a polygon mirror that rotates by a motor and continuously reflects a laser beam, and a focusing lens that is located between the polygon mirror and the semiconductor wafer and cooperates with the polygon mirror to form the laser beam into a line beam.

[0047] The above line beam forming device (30) forms a continuous wave infrared laser beam having a wavelength of 900 nm or more generated from a laser beam generating device into a line beam having a length greater than the diameter of a semiconductor wafer. A wafer transfer robot (6) including a support device for supporting a semiconductor wafer can move a semiconductor wafer on which a line beam is being irradiated, so that a full-scale scan can be performed.

[0048] As a result, according to the present invention, by very quickly evaporating and removing residual ultrapure water and IPA, etc., inside the micro-pattern after cleaning a semiconductor wafer using a continuous wave infrared laser line beam, damage to the pattern due to capillary force is prevented, and compared to an existing expensive CO2 supercritical fluid drying device, the price is very low, the process is simple and safe, the drying cost is very low, and it has the advantage of being easily integrated into an existing wet cleaning equipment.

[0049] The present invention can be specifically applied to the following fields.

[0050] 1. Wafer drying process using existing CO2 supercritical fluid

[0051] 2. Wafer drying process using existing IPA replacement

[0052] Above, the above content is merely an example of a preferred embodiment of the present invention, and it should be recognized that those skilled in the art can make modifications and changes to the present invention without changing the gist of the present invention.

Claims

1. A semiconductor wafer drying device for quickly evaporating liquid existing between micro-patterns on the surface of a semiconductor wafer. A support device that supports a semiconductor wafer; A laser beam generating device that generates a laser beam; A line beam forming device that forms a laser beam generated from the laser beam generating device into a line beam having a length greater than the diameter of the semiconductor wafer and irradiates the line beam onto the semiconductor wafer; and A semiconductor wafer drying device characterized by including a moving device that moves a line beam or a semiconductor wafer so that the line beam scans the entire semiconductor wafer.

2. In paragraph 1, A semiconductor wafer drying device characterized in that the above laser beam generating device generates a continuous wave infrared laser beam having a wavelength of 900 nm or more.

3. In paragraph 1, The above line beam forming device is, A polygon mirror that continuously reflects a laser beam while rotating by a motor, A semiconductor wafer drying device characterized by including a focusing lens positioned between the polygon mirror and the semiconductor wafer and forming a line beam in cooperation with the polygon mirror.

4. In paragraph 3, A semiconductor wafer drying device, characterized in that the above polygon mirror includes 6 to 10 facets that reflect a laser beam.

5. In paragraph 3, A semiconductor wafer drying device, characterized in that the above focusing lens is an F-theta lens or a telecentric lens.

6. Wafer transfer device for transferring semiconductor wafers; and In a semiconductor wafer wet cleaning facility including a wet cleaning chamber for semiconductor wet cleaning, A semiconductor wafer wet cleaning facility, comprising: a line beam forming device integrated within a wafer transport device or within the wet chamber, which forms a laser beam into a line beam to complete wet cleaning within the wet chamber or to irradiate a semiconductor wafer transported by the wafer transport device; wherein the line beam forming device comprises: a polygon mirror that rotates by a motor and continuously reflects a laser beam; and a focus lens that is positioned between the polygon mirror and the semiconductor wafer and cooperates with the polygon mirror to form the laser beam into a line beam.

7. In paragraph 6, The above line beam forming device is a semiconductor wafer wet cleaning equipment characterized in that it forms a continuous wave infrared laser beam having a wavelength of 900 nm or more generated from a laser beam generating device into a line beam having a length greater than the diameter of the semiconductor wafer.

8. In paragraph 7, A semiconductor wafer wet cleaning facility further comprising a wafer transfer robot including a support device for supporting a semiconductor wafer, wherein the wafer transfer robot moves a semiconductor wafer to which a line beam is irradiated so that the semiconductor wafer is scanned in its entirety.

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