JPH04318929A - Washing method and wet etching method of substrate and device thereof - Google Patents

Abstract

PURPOSE:To provide a washing device and a washing method preventing the reattachment of foreign matters through several thousand or several dozen thousand foreign matters (called dust and particles generally) attached on a rear are reattached on the surface of a substrate by the handling (tweezers. vacuum suction, etc.) of the substrate and the yield of aimed semiconductor devices, etc., is deteriorated in a washing method and a wet etching method which have been used for manufacturing the semiconductor devices, etc. CONSTITUTION:A washing liquid 5, from which foreign matters are filtered, is fed continuously from the lower sections of each tank of a plurality of independent washing tanks 3, thus continuously overflowing said washing (or etching) liquid from the upper sections of the washing tanks 3. Substrates 1 are immersed successively in the washing liquid 5 from lower sections one by one at every tank, the substrates 1 are washed near the surfaces of the washing liquid 5 while foreign matters 6 adhering on the substrates 1 are removed, and foreign matters removed are discharged instantaneously outside the tanks by the overflow of the washing liquid, thus preventing the reattachment of foreign matters.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for cleaning and wet etching a substrate (for example, a silicon wafer) in the manufacture of semiconductor devices and the like.

0002

[Background Art] During the manufacturing process of semiconductor devices, when foreign matter (generally called dust or particles) adheres to a substrate, pattern defects (
For example, wiring between individual elements in an LSI may become short-circuited, causing the device to no longer perform its intended function, which causes a decrease in yield in the manufacturing process.

Furthermore, in recent years, semiconductor devices, etc.
As miniaturization (line width of 1 μm or less) and higher density are being promoted, the size of problematic foreign particles is becoming smaller year by year, and there is a need to extremely reduce their number.

[0004] Particularly, the substrate cleaning process is frequently used between each process, and since it affects subsequent processes, foreign matter that adheres during cleaning is an important problem.

On the other hand, the conventional cleaning method (FIG. 3)
As shown in the cross-sectional schematic diagram of the cleaning method, a substrate 31 is placed in a carrier 32 (usually called a cassette; in a silicon semiconductor process, one cassette generally holds 25 substrates), and a foreign matter filtering device 34 removes foreign matter. By immersing the substrate 31 in the cleaning liquid 35 from which it has been removed (FIG. 3b), the substrate 31 is cleaned (removal of impurities, etc.), and at the same time foreign substances adhering to the substrate 31 are peeled off and taken into the cleaning liquid 35. Then, by sufficiently supplying the cleaning liquid 35 to replace the liquid, foreign matter in the cleaning tank is removed and foreign matter adhering to the substrate 31 is removed.

[0006]

[Problems to be Solved by the Invention] However, with the above-mentioned cleaning method, there is a problem in removing foreign substances, and this problem can be solved by (
The following description is based on Figure 4).

First, in the substrate 31 shown in FIG. 3, the back surface on which no elements are formed is in contact with tweezers, vacuum tweezers, a vacuum chuck (which holds the substrate in place by vacuum), a conveyor belt, etc. Therefore, thousands to tens of thousands of foreign objects (foreign objects 36 in FIG. 4) are attached (this varies greatly depending on the conditions). In this state, when the substrate 31 is cleaned by the method shown in FIG. 3, the foreign matter on the back surface of the substrate A37 is removed by the cleaning liquid 35, and at the same time, it is also re-attached to the surface of the opposite substrate B38. Moreover, this phenomenon occurs when the substrate 31 is immersed in the cleaning liquid 35, as shown in FIG.
Some of the foreign matter on the back surface of the substrate A37 peels off near the surface of the cleaning liquid 35 and re-attaches to the surface of the substrate B38 near the surface of the cleaning liquid. (Whether redeposition occurs near the surface of the liquid or due to diffusion of the liquid in the liquid depends on the type of cleaning liquid.) As mentioned above, when foreign matter on the back side re-attaches to the front surface, foreign matter attached to the substrate cannot be completely removed (the removal rate is about 20 to 95% depending on the cleaning solution), so depending on the number of foreign particles attached to the back side, it may be used to prevent short circuits between wiring or for the purpose of post-processing. This affects the pattern shape, leading to a decrease in the yield of semiconductor devices, etc.

Furthermore, although the above description was about cleaning, exactly the same thing occurs in commonly used wet etching.

An object of the present invention is to provide a cleaning method and a wet etching method that eliminate the conventional drawbacks as described above.

0010

[Means for Solving the Problems] In order to solve the above problems, the cleaning method and wet etching method of the present invention remove foreign matter from the lower part of each of a plurality of independent cleaning (or wet etching) tanks. filtered wash (or
By continuously supplying the etching solution, cleaning (
Alternatively, while continuing to overflow the cleaning (or etching) solution from the top of the wet etching tank,
The substrates are sequentially immersed in the cleaning (or etching) solution from the bottom so that one substrate is in each bath, and then the cleaning (or etching) solution is applied.
Alternatively, the substrate is cleaned (etched) near the surface of the etching solution.
At the same time as etching), remove foreign matter adhering to the substrate, and wash the removed foreign matter (or etching).
This structure is achieved by immediately discharging the etching solution to the outside of the tank due to overflow, thereby preventing foreign matter from adhering to the substrate again.

[0011]

[Operation] With the above-described configuration, the present invention cleans only one substrate by placing it in an independent cleaning tank, so that foreign matter on the back side of the substrate is removed and simultaneously discharged to the outside of the cleaning tank together with the cleaning solution. Foreign matter can be removed without re-adhering to the surface of the substrate. This makes it possible to perform cleaning that completely removes foreign substances even in the production of semiconductor devices and the like using fine patterns. Further, by simultaneously processing a plurality of substrates using a plurality of cleaning tanks, the throughput of substrate cleaning is not reduced.

0012

DESCRIPTION OF THE PREFERRED EMBODIMENTS A cleaning apparatus and a cleaning method thereof according to a first embodiment of the present invention will be described in detail below with reference to the drawings.

(FIG. 1) is a schematic cross-sectional view of a cleaning device showing a first embodiment of the present invention. (FIG. 1), 1 is a substrate to be cleaned such as a semiconductor substrate, 2 is a carrier that supports the substrate, 3 is a cleaning tank, 4 is a foreign matter filtering device, 5 is a cleaning liquid,
9 is a cleaning liquid supply pipe, and 10 is a cleaning liquid recovery tank.

First, in FIG. 1A, after foreign substances in the cleaning liquid are removed by the foreign substance filtering device 4, the cleaning liquid is supplied from the lower part of the plurality of cleaning tanks 3 through the cleaning liquid supply pipe 9. The cleaning liquid 5 from which foreign substances have been removed is constantly supplied, overflows at the upper part of the cleaning tank 3, and is discharged to the outside of the tank.

On the other hand, a plurality of substrates 1 are set in a carrier 2 which is structured so that one substrate can be inserted into each independent cleaning tank 3.

Next, the substrate 1 is slowly placed into the cleaning tank 3 while being supported by the carrier 2. At this time, 1
Only one substrate 1 can be placed in each cleaning tank 3.

Then, the entire substrate 1 is placed in the cleaning liquid 5 (
1b), after cleaning the substrate 1 by immersing it in the cleaning liquid 5 for a predetermined time, the carrier 2 is pulled up and the substrate 1 is taken out from the cleaning tank 3.

During the above-mentioned cleaning, when the substrate 1 was put into the cleaning tank 3, as shown in the diagram for explaining the flow of foreign substances (FIG. 2), foreign substances were found attached to the back surfaces of the substrate A7 and the substrate B8. A part of the foreign matter 6 falls off at the upper part of the cleaning liquid 5 (or the cleaning tank 3) and is taken into the cleaning liquid 5 (the foreign matter 6 is not completely removed). Furthermore, since the cleaning liquid 5 continues to be supplied from the bottom, the cleaning liquid 5 near the top containing a large amount of foreign matter 6 is immediately discharged from the cleaning tank 3. Foreign matter does not adhere to the surface of the substrate 1 again.

Furthermore, other than the upper part of the cleaning tank 3 (in the cleaning liquid)
Even foreign matter that has peeled off from the back side of the board 1 can be removed from the board 1.
Since the moving direction of the cleaning liquid 5 flowing near the back surface of the substrate is fixed (flowing upward), the cleaning liquid near the back surface of the substrate that contains foreign matter rarely reaches the surface of the substrate, and foreign matter on the surface of the substrate does not increase. .

Furthermore, in FIG. 1, it is described that the cleaning liquid 5 overflowing from the cleaning tank 3 is recovered and circulated by the cleaning liquid recovery tank 10, but this is not particularly necessary.

Examples of the cleaning liquid include pure water from which metal ions have been removed, acids and alkalis such as sulfuric acid, nitric acid, hydrochloric acid, and ammonia, as well as organic solvents.

The cleaning apparatus and cleaning method have been described above, and by replacing the cleaning liquid 5 with an etching liquid, it is possible to prevent the foreign matter 6 from re-adhering to the surface of the substrate 1, in exactly the same manner as described in the above-mentioned cleaning method. can.

[0023]

[Effect of the invention] As is clear from the detailed explanation above,
The present invention can remove foreign matter adhering to the back surface of a substrate during cleaning or wet etching without re-adhering to the surface where elements are formed, and does not cause a decrease in yield in the cleaning or wet etching process. Therefore, it is highly effective to implement it.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of a cleaning device in a first embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view for explaining the flow of foreign matter in the first embodiment of the present invention.

FIG. 3 is a schematic cross-sectional view of a cleaning device for explaining a conventional cleaning method.

FIG. 4 is a diagram for explaining problems in the conventional cleaning method.

[Explanation of symbols]

1　Substrate board 2 Carrier 3 Washing tank 4 Foreign matter removal device 5　Cleaning liquid 6 Foreign matter 7 Substrate A 8 Substrate B 9 Cleaning liquid supply piping 10 Cleaning liquid recovery tank 31　Substrate 32 Carrier 33 Washing tank 34 Foreign matter filtration device 35 Cleaning liquid 36 Foreign matter 37 Substrate A 38 Substrate B

Claims (4)

[Claims] 1. By continuously supplying a cleaning liquid from which foreign substances have been filtered from the lower part of each of a plurality of independent cleaning tanks, the cleaning liquid continues to overflow from the upper part of the cleaning tank, and the substrate is transferred to each tank. By sequentially immersing each substrate in the cleaning liquid from the bottom, one substrate at a time, the substrates are cleaned near the surface of the cleaning liquid, and at the same time, foreign matter adhering to the substrate is removed, and the removed foreign matter is soaked in the cleaning liquid. A cleaning method characterized in that the foreign matter is immediately discharged outside the tank by overflow to prevent the foreign matter from adhering to the substrate again. 2. A plurality of independent wet etching tanks, by continuously supplying an etching solution from which foreign substances have been filtered from the lower part of each tank, the etching solution continues to overflow from the upper part of the wet etching tank, By sequentially immersing one substrate in the etching solution from the bottom in each bath, the substrate is etched by the etching solution near the surface of the etching solution, and at the same time, foreign matter adhering to the substrate is removed. remove,
A wet etching method in which the removed foreign matter is immediately discharged to the outside of the tank by overflow of the etching solution, thereby preventing the foreign matter from adhering to the substrate again. 3. A plurality of independent cleaning tanks each capable of cleaning one substrate in an upright state, a mechanism for removing foreign matter from the cleaning solution, and a mechanism for transferring the cleaning solution from which the foreign matter has been removed to the plurality of cleaning tanks. A cleaning device comprising: a mechanism for supplying substrates to the substrate; and a mechanism for simultaneously loading one substrate into each of the plurality of cleaning tanks. 4. A plurality of independent wet etching tanks each capable of etching one substrate in an upright state, a mechanism for removing foreign matter in the etching solution, and a mechanism for removing the foreign matter in the etching solution from the plurality of wet etching tanks. A wet etching apparatus comprising: a mechanism for supplying the substrate to a plurality of wet etching tanks, and a mechanism for simultaneously loading one substrate into each of the plurality of wet etching tanks.