JPH04115529A - Washing method and device - Google Patents

Abstract

PURPOSE:To prevent whirls within a washing liquid from being produced without increasing flow of supplied washing liquid and foreign objects which float on a surface of the washing liquid from stagnating by placing a liquid-absorbing pipe near a surface within the washing liquid and then discharging one part of the washing liquid using the liquid-absorbing pipe. CONSTITUTION:An upper side of a washing tank 1 is overflown due to supply of a washing liquid 2 from a lower side continuously through a flowing-in hole 1a which is provided on a bottom surface and then a semiconductor wafer W is buried and dipped into the inside washing liquid 2. A liquid-absorbing pipe 3 is placed near a surface within the liquid at any location on the surface of the washing liquid 2 within the washing tank 1 with an opening 3a facing downward and absorbs one part of the washing liquid 2 and then discharges it, thus preventing whirls within the washing liquid from being produced even without increasing flow of the supplied washing liquid and foreign objects which float on a surface of the washing liquid from stagnating.

Description

[Detailed Description of the Invention] [Summary] It relates to a cleaning method and a cleaning device, and particularly relates to a cleaning tank in which a plurality of thin plate-shaped bodies whose principal surfaces are substantially vertical and which are arranged in parallel at intervals in a direction in which the principal surfaces overlap. When cleaning a thin plate-like object, such as a semiconductor wafer, by immersing it in a cleaning solution, the process is performed while the cleaning solution overflows from the cleaning tank. For the purpose of preventing stagnation of foreign matter floating on the surface of the cleaning liquid, the opening of the liquid suction pipe that sucks liquid from the end opening or the liquid supply pipe that flows out the liquid from the end opening is directed downward. Disposed near the surface of the cleaning liquid in the cleaning tank, so that a part of the cleaning liquid is discharged through the liquid suction pipe, or a cleaning liquid of the same quality as the cleaning liquid is discharged from the liquid supply pipe into the cleaning liquid. Configure.

[Industrial application field]

The present invention relates to a cleaning method and a cleaning device, and more particularly, the present invention relates to a cleaning method and a cleaning device, and in particular, a plurality of thin plate-like bodies arranged in parallel at intervals in a direction in which the major surfaces are substantially vertical and the major surfaces overlap are immersed in a cleaning liquid in a cleaning tank. The present invention relates to cleaning of the thin plate-like object, such as a semiconductor wafer.

In the manufacturing of semiconductor devices, there is a cleaning process for semiconductor wafers.In order to reduce the unit cost of the process, 20 to 30 wafers are held in the above arrangement using a frame-shaped holder called a carrier, and cleaning liquid in a cleaning tank is used together with the carrier. This is done by immersing it in water. The cleaning solution includes HF/H to remove the surface oxide film.
A chemical solution such as 2O or pure water from which the chemical solution is removed is used. In either case, it is important to ensure that the object to be removed is removed and that foreign matter such as dust does not adhere to the surface.

[Conventional technology]

FIG. 3 is a schematic sectional view of a conventional example of an apparatus for performing the above-mentioned cleaning.

In the same figure, ■ is a cleaning tank, and in the cleaning tank l, cleaning liquid 2 is continuously supplied from the bottom through an inflow hole 1a provided at the bottom and overflows at the top, and the semiconductor wafer W is poured into the cleaning liquid 2 inside. Bury and immerse. As described above, the wafers W are held by a carrier in a state in which a plurality of wafers are arranged in parallel with their main surfaces substantially perpendicular and at intervals in the direction in which the main surfaces overlap, and are immersed together with the carrier. Here, illustration of the carrier is omitted.

In this cleaning, the cleaning liquid 2 continuously passes between the wafers W and the outside of the group of wafers from bottom to top, strokes the surfaces of the wafers W, and exerts a cleaning effect.

[Problem to be solved by the invention]

However, in this method of cleaning, as the wafers W become larger according to the current trends, the cleaning tank 1 becomes larger and relatively more of the cleaning liquid 2 flows outside the group of wafers W, as shown in FIG. A vortex 2a is generated inside the cleaning liquid 2, and a stagnation 2b is generated on the surface of the cleaning liquid 2.

This vortex 2a causes uneven cleaning. Also, stagnation 2b
attracts dust-like foreign matter adhering to the wafer W or floating up due to friction between the wafer W and the carrier, and prevents the foreign matter from flowing out together with the overflow of the cleaning liquid 2. The foreign particles floating and stagnant on the surface of the cleaning liquid 2 adhere to the wafer W when the wafer W is pulled up from the cleaning liquid 2, deteriorating the quality of the cleaning result.

In order to prevent such uneven cleaning and adhesion of foreign matter, the flow rate of the cleaning liquid 2 supplied to the cleaning tank I should be increased to prevent the generation of vortices 2a and the stagnation of floating foreign matter. Therefore, the required supply flow rate becomes extremely large.

Therefore, the present invention provides a cleaning method that prevents the generation of vortices such as the vortex 2a and the stagnation of floating foreign matter such as foreign matter particles, without increasing the supply flow rate of the cleaning liquid in the above-mentioned cleaning. The purpose is to provide cleaning equipment.

[Means to solve the problem]

In order to achieve the above object, in the cleaning method of the present invention, a plurality of thin plate-shaped bodies whose principal surfaces are substantially vertical and which are arranged in parallel at intervals in a direction in which the principal surfaces overlap are buried in a cleaning liquid in a cleaning tank. When cleaning the thin plate-like body by immersion, the cleaning liquid is supplied from below in the cleaning tank and continuously overflows, while the opening of the liquid suction pipe that sucks the liquid from the end opening is directed downward. The cleaning liquid is disposed near the surface of the cleaning liquid, and a portion of the cleaning liquid is discharged through the liquid suction pipe. In that case, it is desirable that the openings be located at locations where the cleaning liquid stagnates on the surface.

Alternatively, in this cleaning method, the liquid suction pipe is replaced with a liquid supply pipe that drains the liquid from the end opening, and instead of discharging a part of the cleaning liquid, a cleaning liquid of the same quality as the cleaning liquid is discharged into the cleaning liquid. You may also do this. In that case, it is desirable that the cleaning liquid be discharged intermittently or in a pulsating manner.

In addition, the cleaning device has a cleaning tank and a liquid suction pipe,
In the cleaning tank, cleaning liquid is continuously supplied from the bottom and overflows, and the object to be cleaned is submerged and immersed in the cleaning liquid, and the liquid suction pipe has a function of sucking the liquid from the opening at the end. It is possible at any time to place the opening facing downward near the surface of the cleaning liquid, or to evacuate it from above the cleaning tank, and when the opening is placed in the cleaning liquid, the cleaning liquid It is characterized by being inhaled and expelled in part.

Alternatively, in this cleaning device, a liquid supply pipe is provided instead of the liquid suction pipe, and the liquid supply pipe has a function of sucking liquid from the end opening of the liquid suction pipe. The opening may have a function of flowing out, and when the opening is placed in the cleaning liquid, a cleaning liquid having the same quality as the cleaning liquid may flow out. In that case, it is desirable that the liquid supply pipe is capable of causing the cleaning liquid to flow out intermittently or in a pulsating manner.

[For production]

The generation of the vortex 2a and the stagnation of floating foreign matter explained in FIG. 3 are caused by the fact that when the supply flow rate of the cleaning liquid 2 is small, part of the cleaning liquid 2 flows to the opposite side of the overflow at the surface, and the liquid stagnates at the stagnation 2b. It is created to crawl inside.

The present invention focuses on this point, and takes measures to prevent the cleaning liquid from penetrating by (1) closing the cleaning liquid to eliminate the above-mentioned penetration of the cleaning liquid, or (2) ensuring that the flow of the cleaning liquid at the surface area is entirely directed toward the overflow. This prevents the generation of vortices such as vortex 2a and the stagnation of floating foreign matter such as foreign matter particles, even without increasing the supply flow rate. The above item (2) is realized, and the liquid supply pipe realizes the above item (2).

The location where the opening of the liquid suction pipe or liquid supply pipe is placed close to the surface of the cleaning liquid is clearly most effective in the area where the cleaning liquid stagnates on the surface, and even if the opening is deviated from this position, sufficient effects can still be obtained. I can do it.

Further, when the cleaning liquid is discharged from the liquid supply pipe intermittently or in a pulsating manner, the flow of the cleaning liquid in the cleaning tank is shaken, and the unevenness of cleaning is further reduced.

The reason why the liquid suction pipe or the liquid supply pipe in the cleaning device can be retracted from the top of the cleaning tank is because when the object to be cleaned (thin plate-like object in the cleaning method) is taken in and out of the cleaning tank,
This is to prevent the liquid suction pipe or liquid supply pipe from getting in the way.

〔Example〕

Embodiments of the present invention will be described below with reference to FIGS. 1 and 2. FIG. 1 is a schematic sectional view of the first embodiment of the apparatus for carrying out the first embodiment of the method, and FIG. 2 is a schematic sectional view of the second embodiment of the apparatus for carrying out the second embodiment of the method.
This is a schematic cross-sectional view of an example, and the same reference numerals indicate the same objects throughout the drawings.

In FIG. 1, the first embodiment of the cleaning device is obtained by adding a liquid suction pipe 3 to the conventional device described in FIG.

The liquid suction pipe 3 has a function of sucking liquid from an end opening 3a, and is arranged near the submerged surface of the cleaning liquid 2 in the cleaning tank 1 at an arbitrary location with the opening 3a facing downward; It is possible to retreat from above at any time, and the opening 3
When a is placed in the cleaning liquid 2, a part of the cleaning liquid 2 is sucked in and discharged. The above arrangement of the opening 3a and the liquid suction pipe 3
The above-mentioned retraction is performed by movement in the directions of arrows A, B, and C by an adjustment mechanism (not shown) provided in the liquid suction pipe 3.

An example of a cleaning method using this cleaning device (method example 1) is as follows.

That is, in this embodiment, an 8-inch wafer W is cleaned with pure water using a cleaning tank 1 whose upper opening is 30 cm square, and the stagnation 2b mentioned above is in the center of the surface of the cleaning liquid 2. Therefore, the opening 3a of the liquid suction tube 3 was placed at the center, and the test was carried out under the following conditions.

Depth of opening 3a from liquid surface: Approximately 10 mm Cleaning liquid supply flow rate to cleaning tank 1: 20 A/min Liquid suction flow rate through liquid suction pipe 3: 51/min Cleaning time: 10 minutes There, the cleaning liquid 2 is first applied to the surface. The aforementioned stagnation of foreign matter was not visually observed, the cleaning result was even, and the amount of foreign matter attached was less than 10 per wafer W by microscopic observation.

Incidentally, when the liquid suction tube 3 was removed from the example, stagnation of foreign matter was observed, and the amount of foreign matter adhesion decreased to 100% per wafer W.
In addition, in order to eliminate the stagnation of foreign matter with the liquid suction tube 3 removed, the supply flow rate of the cleaning liquid needed to be about twice that of the example.

In order to know the flow state of the cleaning liquid 2 in the case of the example, fine powder was dispersed and mixed into the cleaning liquid 2 to be supplied to the cleaning tank 1.
When observed by irradiating light from the lateral direction, the flow of the cleaning liquid 2 was in a state where the above-mentioned vortex 2a was not generated, as shown in FIG.

Further, in this example, the depth of the opening 3a from the liquid surface was varied in a range of about 1 to 20 mm, but the same results as described above were obtained in all cases. Furthermore, similar results were obtained even if the location of the opening 3a was slightly shifted from the center of the cleaning liquid 2.

Next, in FIG. 2, a second embodiment of the cleaning device is obtained by adding a liquid supply pipe 4 to the conventional device described in FIG.

The liquid supply pipe 4 has a function of flowing out the liquid from the end opening 4a, and, like the liquid suction pipe 3 described above, the liquid supply pipe 4 has the function of flowing out the liquid from the end opening 4a. It can be placed near the inner surface or evacuated from above the cleaning tank l at any time. It can also be done. The above-mentioned arrangement of the opening 4a and the above-mentioned retraction of the liquid supply pipe 4 are performed by movement in the directions of arrows A, B, and C by an adjustment mechanism (not shown), similarly to the liquid suction pipe 3.

An example of a cleaning method (second example of the method) using this cleaning device is as follows.

That is, in this embodiment, as in the first embodiment, an 8-inch wafer W is cleaned with pure water using a cleaning tank 1 whose upper opening is 30 cm square. Since the stagnation 2b occurs in the center of the surface of the cleaning liquid 2,
The test was carried out under the following conditions, with the opening 4a of the liquid supply pipe 4 arranged at the center.

Depth of opening 4a from liquid surface: Approximately 10 mm Flow rate of cleaning liquid supplied to washing tank: 2OA/min Liquid outflow form from liquid supply pipe 4: Intermittent outflow (outflow 10 seconds, pause 5 seconds) Same as above liquid outflow Hourly flow rate: 51/min cleaning time
: 10 minutes At that time, no stagnation of the foreign particles mentioned above was visually observed on the surface of the cleaning solution 2, and the cleaning results showed that there was no uneven cleaning and the number of foreign particles attached was less than 10 per wafer W by microscopic observation.

Needless to say, when the liquid supply pipe 4 is removed from this embodiment, it is the same as when the liquid suction pipe 3 is removed in the first embodiment.

In order to find out the flow state of the cleaning liquid 2 in this example, we made the same observation as in the first example.
The flow of the cleaning liquid 2 is as shown in FIG.
was not occurring.

Furthermore, in this embodiment, the liquid outflow form from the liquid supply pipe 4 is changed to continuous outflow (the flow rate is the same as the flow rate at the time of outflow described above) or pulsating outflow (the above-mentioned pause is changed to outflow of 201/min). In both cases, the same results as above were obtained.

However, intermittent outflow or pulsating outflow shakes the flow of the cleaning liquid 2 in the cleaning tank I, and although this is an area that is difficult to determine with the current detection ability, in principle it can further reduce uneven cleaning.

In addition, we tried varying the depth of the opening 4a from the liquid surface in a range of about 1 to 20 mm, but the same results as above were obtained in each case. Similar results were obtained even if the image was shifted slightly from the center.

In the above-mentioned embodiment, the liquid suction pipe 3 or the liquid supply pipe 4 is used as one and the conditions are specified. However, if the stagnation 2b occurs at multiple locations, It is effective to use a plurality of conditions, and the conditions are not limited to those in the example (they can be changed as appropriate.Also, in the example, the semiconductor wafer W was used as the object to be cleaned, but the object to be cleaned could be Similar results can be obtained with a thin plate-like body other than the semiconductor wafer W.

〔Effect of the invention〕

As explained above, according to the present invention, a plurality of thin plate-like bodies whose principal surfaces are substantially vertical and which are arranged in parallel at intervals in the direction in which the principal surfaces overlap are immersed in a cleaning solution in a cleaning tank. , regarding cleaning of the thin plate-like object, such as a semiconductor wafer,
The cleaning method and cleaning equipment must be used to overflow the cleaning liquid from the cleaning tank, so that the supply flow rate of the cleaning liquid must be increased (in addition, the cleaning method and cleaning equipment must be designed to prevent the generation of vortices in the cleaning liquid and the stagnation of foreign particles floating on the surface of the cleaning liquid). This has the effect of making it possible to reduce the amount of cleaning liquid used while ensuring high quality cleaning results.

[Brief explanation of drawings]

Fig. 1 is a schematic sectional view of the first embodiment of the apparatus for carrying out the first embodiment of the method, Fig. 2 is a schematic sectional view of the second embodiment of the apparatus for carrying out the second embodiment of the method, and Fig. 3 is a conventional example of the apparatus. This is a schematic cross-sectional view. In the figure, ■ is the cleaning tank, 1a is the inflow hole, 2i is the cleaning liquid, 2a is the vortex, 2b is the stagnation, 3 is the liquid suction pipe, 4 is the liquid supply pipe, 3a and 4a are the end openings, and A, B, and C are the The direction of adjustment movement, D is the foreign object, and W is the semiconductor wafer. 1; +fC, floating tank 2 cleaning liquid 3α 紓 口 vv″ + conductor L-αj input 3 suction tubes A, B, C′ 6 circumferential movement force 薗 1; ?1 〒っ) (J1) Fortune-telling 1 Kantabi Ia 10 Provisions (Dan db ￥ 1121

Claims (1)

[Scope of Claims] 1) A plurality of thin plate-like bodies whose principal surfaces are substantially vertical and arranged in parallel at intervals in the direction in which the principal surfaces overlap are immersed in a cleaning solution in a cleaning tank, and the thin plate-like bodies are immersed in a cleaning solution in a cleaning tank. When cleaning, in the cleaning tank, the cleaning liquid is supplied from below and continuously overflows, while the opening of the liquid suction pipe that sucks the liquid from the end opening faces downward and near the submerged surface of the cleaning liquid. A cleaning method characterized in that the cleaning liquid is disposed in a vacuum cleaner and a part of the cleaning liquid is discharged through the liquid suction pipe. 2) The cleaning method according to claim 1, wherein the opening is arranged at a location where the cleaning liquid stagnates on the surface. 3) In the cleaning method according to claim 1 or 2, the liquid suction pipe is replaced with a liquid supply pipe that drains the liquid from an opening at the end, and instead of discharging a part of the cleaning liquid, a liquid is added to the cleaning liquid. A cleaning method characterized by draining a cleaning solution of the same quality as the cleaning solution. 4) The cleaning method according to claim 3, wherein the cleaning liquid is discharged intermittently or in a pulsating manner. 5) It has a cleaning tank and a liquid suction pipe, the cleaning tank is continuously supplied with cleaning liquid from below and overflows, and the object to be cleaned is submerged and immersed in the cleaning liquid, and the liquid suction pipe has the function of sucking liquid from the end opening,
It is possible at any time to place the opening facing downward near the surface of the cleaning liquid or to withdraw it from above the cleaning tank, and when the opening is placed in the cleaning liquid, a portion of the cleaning liquid is removed. A cleaning device characterized in that it sucks in and discharges. 6) The cleaning device according to claim 5, further comprising a liquid supply pipe instead of the liquid suction pipe, and the liquid supply pipe has an end opening instead of the function of sucking liquid from the end opening of the liquid suction pipe. 1. A cleaning device having a function of flowing out a liquid from an opening, and when the opening is placed in the cleaning liquid, a cleaning liquid having the same quality as the cleaning liquid flows out. 7) The cleaning device according to claim 6, wherein the liquid supply pipe is capable of causing the cleaning liquid to flow out intermittently or in a pulsating manner.