JPH0323635A - Method and apparatus for cleaning of semiconductor substrate - Google Patents

Abstract

PURPOSE:To execute a sufficient cleaning operation and to enhance a quality by a method wherein steam is supplied to a main-face part including a recessed part formed in a semiconductor substrate, ice is formed and, after that, the cleaning operation is executed by using a cleaning liquid. CONSTITUTION:A pressure of a cleaning tank 11 is reduced by using a pressure- reduction and pressurization apparatus 13. A cooler 19 is operated; a wafer 1 is cooled; steam 6 is supplied from a steam generator 14. Ice 3 is formed on the whole surface of the wafer 1. Then, a cleaning-liquid supply port 17 is opened; a cleaning liquid 4 is supplied. Since the cleaning tank 11 is in a reduced pressure state, the cleaning liquid 4 of a certain amount enters a trench 2. Then, a temperature of the cooler 19 is controlled in such a way that the ice 3 is melted by the cleaning liquid 4. Thereby, the ice 3 is transformed into water; this water is collected at the bottom of the trench 2. The cleaning liquid 4 is dissolved in the water; a gas 5 inside the trench 2 rises as bubbles 5, and the bubbles enter the trench 2. Then, the cleaning tank 11 is set to a prescribed pressurization state; the cleaning liquid 4 is diffused up to the trench 2; this trench is cleaned perfectly.

Description

[Detailed description of the invention] [. Industrial Icheon Field] The present invention cleans semiconductor planting boards in which concave portions are formed! #
The present invention relates to a method for cleaning a conductor substrate and a cleaning device used therefor.

[Prior Art] In recent years, as semiconductor integrated circuits have become more highly integrated and miniaturized, the circuit patterns formed on semiconductor substrates (hereinafter simply referred to as "Quehachi") have also become smaller and their structures have become more complex. It's coming. For this reason, a technique has been adopted in which Shiro is formed on the wafer and elements are formed in that portion. In addition, as higher integration and miniaturization progress, things that were not a problem in the past have started to emerge as major problems, and foreign substances such as contaminants on wafers have started to cause problems due to their characteristics. ,
They must be reliably removed by a cleaning process. A cleaning process is performed in a process after machining when forming the recesses, or in a process to remove oxides formed on the wafer.

FIG. 4 is a diagram showing a schematic configuration of a conventional cleaning device that performs this type of cleaning process. In the figure, (1) is the wafer to be processed, (4) is the cleaning liquid that cleans the wafer (1), and (11) is the cleaning liquid (4) that is supplied and the wafer (1) is immersed in it. (12) is a cleaning tank (11).
) is a wafer support stand on which a wafer (1) is placed.

Next, a cleaning method using the cleaning apparatus configured in this manner will be explained. First, cleaning 1! (11) Add cleaning solution (4
) is supplied and the cleaning liquid (4) is filled to the specified height of the cleaning NI (11).After this, the wafer (1) is transferred into the cleaning tank (11) and placed on the wafer support (l2). Place it. In this way, the quefer (l) is immersed in the cleaning solution (4).
). At this time, the cleaning liquid (4) is normally circulated. The wafer (1) is cleaned in this way, and the wafer (1) has a trench (2) formed therein. This trench (2) has an opening width of 1 μm or less and a depth of 2 to 2 μm, for example.
It is formed to have a thickness of about 0 μm. It is necessary to clean not only the main surface of the wafer (1) but also the inside of the trench (2).

By the way, in addition to the above-mentioned cleaning method using circulation, wafers (
In order to further increase the cleaning efficiency as the cleaning method 1), a cleaning method in which ultrasonic waves are applied to the cleaning liquid <<4>> and the wafer (1), or the cleaning liquid (4) is pressurized is also used. Furthermore, after placing the wafer (1) on the wafer support table (12), the pressure inside the cleaning top (11) is reduced, and in that state, the cleaning liquid (4) is supplied to clean the wafer (.1). A method is also used.

[Problems to be Solved by the Invention] The conventional cleaning method is as described above, and the width of the opening formed on the wafer (1) is 1 μm or less and the depth is 2 μm.
The inside of the fine trench (<2>) of 20 μm to 20 μm was not completely cleaned.

That is, as shown in FIG. 5, even if the cleaning liquid (4) is supplied to the wafer (1) on which the trenches (2) are formed, gas <5> remains in the trenches (2), and the cleaning liquid (4) remains in the trenches (2). ) does not spread over the entire surface of the trench (2). This is because the opening width of the trench (2) is extremely small, so the surface tension of the cleaning liquid (4) prevents it from penetrating into the trench (2). Now, the gas (5) inside the trench (2) and the cleaning liquid (4)
》 This is because it is difficult to replace .

For this reason, there was a problem in that the conventional cleaning method could not completely remove the foreign substances in the trench (2), and the foreign substances remained and the reliability was impaired.

The present invention has been made in order to solve the above-mentioned problems, and is a quenching method in which the cleaning liquid is spread throughout the recesses formed on the wafer, and the quality of the wafer is improved by performing suitable cleaning. The object of the present invention is to obtain a cleaning method and a cleaning device used therein.

[Means for Solving the Problems] A method for cleaning a semiconductor substrate according to the present invention brings a processing tank in which the substrate is stored into a reduced pressure state, supplies water vapor to the cooled microplate, and cleans the semiconductor substrate formed on the substrate. After ice is formed on the main surface portion including the recessed portions, a cleaning liquid is supplied to the substrate to perform cleaning.

Further, the cleaning device used in the method of cleaning semiconductor substrates according to the present invention includes a closed processing tank and a cooling device provided within the processing tank for cooling a semiconductor magazine plate placed in the processing tank. means, a water vapor generating means for supplying the substrate with water vapor that can adhere to a recess formed in the substrate, a cleaning liquid supply means for supplying the substrate with a cleaning liquid capable of dissolving the water vapor, and a cleaning liquid supplying means for supplying the substrate with a cleaning liquid capable of dissolving the water vapor; It is equipped with depressurization/pressurization means for bringing the pressure into a depressurized or pressurized state.

[Operation] In the present invention, water vapor adhering to the recesses formed on the substrate is deposited over the bottom of the recesses of the cutting board in a reduced pressure atmosphere, and is cooled and turns into ice, which forms over the entire surface of the recesses. be done. Since the cleaning liquid is supplied in this state, the ice is dissolved in the cleaning liquid, and the entire surface of the recessed portion is cleaned.

Further, the water vapor generating means in the present invention generates water vapor that adheres to the bottom of a recess formed in the substrate when the substrate is in a reduced pressure state. The cooling means provided under the substrate converts water vapor adhering to the recesses of the substrate into ice, and the cleaning liquid supply means supplies cleaning liquid to the substrate to melt the ice and clean the recesses.

[Example] Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing a schematic configuration of a cleaning device according to an embodiment of the present invention. In the figure, (1) is a wafer to be cleaned, (l1) is a cleaning tank that accommodates this wafer (1), and has a main body (lla) and a lid that can be opened and closed on the top of this main body (lla). body (ttb), and a sealed space is formed inside. (l2
) is provided inside the cleaning m (11) 'i11-A
Support stand (12), (13) & t tip ffll cleaning m (
11) (7) A vacuum pressurizer connected to the diagonally upper part to reduce and pressurize the inside of the cleaning tank <<I1>, (10 is a vacuum pressurizer <<I3)
This is a steam generator that is located on the side opposite to the washing tank (11) and whose tip is connected to the diagonally upper part of the washing tank (11). (l5) is a temperature regulator (l6) attached to the side wall of the cleaning treetop (l!) to adjust the temperature.
) is a controller that is electrically connected to this temperature regulator (15), and (17) is a supply whose tip is inserted into the side wall of the washing ill (11) and supplies processing liquid into the washing M (eye). The port 08) is a discharge port provided at the bottom of the cleaning MI (II) for discharging the processing liquid. (l9) is the wafer support stand《
This is a cooler for cooling the wafer (1) installed inside the wafer (1).

Next, a cleaning method using the cleaning apparatus configured as described above will be explained.

First, the lid (llb) is opened, and the wafer (1.) is transferred to the wafer support stand (l2) in the cleaning tank (ll).
After 1 L of loading, the lid body (Ilb) is closed to seal the inside of the cleaning tree (11). At this time, cleaning WJ (1
1) is at atmospheric pressure, and the trench (1) of the wafer (1) is under atmospheric pressure.
2), gas (5) remains inside (Figure 2(a)). Next, operate the pressure reducer/pressurizer <l3> and clean the cleaning tank (I
1) Reduce the pressure inside to the specified pressure. Further, the cooler (l9) is operated to cool the wafer (1) to a predetermined temperature. After that, the steam generator (14) is operated to generate steam (6).
is generated and water vapor (6) is supplied into the cleaning tank (11). As a result, water vapor (6) is attached to the main surface of the wafer (1) and inside the trench (2), but the wafer (1)
Since it is being cooled, ice (3) forms over its entire surface. In addition, inside the cleaning tank (I1), cooling 3 (19
) The temperature of the space excluding the area around the wafer (1) is 3L! By the operation of the lf7h device (15), water vapor (
6) is maintained above the dew point temperature (Fig. 2(b)).

Next, after the ice (3) is formed, the cleaning liquid supply port (17)
The valve (figure omitted) attached to the is opened, and the cleaning liquid (4) is supplied into the cleaning tank (11).As a result, the water vapor (6) dissolves in the cleaning liquid (4), but the cleaning liquid 4) A trace amount of gas (5) that does not dissolve in the trench (2) remains in the trench (2).Here, since the inside of the cleaning tree (11) is maintained at a reduced pressure state, a certain amount of gas (5) remains in the trench (2). The cleaning liquid (4) enters the state (Fig. 2 (C)).

Next, by controlling and resetting the temperature of the cooler (19), the temperature of the wafer (1) is changed so that the temperature of the ice (3) is changed to that of the cleaning liquid (4).
so that it dissolves in As a result, as shown in No. 3131. The ice (3) begins to melt and turns into water (20), which begins to accumulate at the bottom of the trench (2). In response to the flow of water (20) from the top to the bottom of the trench (2), the hydrophilic cleaning liquid (4) also flows to the bottom of the trench (2) while dissolving the water (20). This water (20
] and the flow (22) of the cleaning liquid (4) pushes out the gas (5) that had accumulated in the trench (2) into bubbles (
21) and rises. These expanded bubbles (21) are sequentially discharged into the space of the cleaning tank (I1) under reduced pressure. In this way, at °C, at the same time as the ice (3) melts, the gas (5) that remained in the trench (2) escapes from the trench (2), and the cleaning liquid also enters the trench (2). (4) comes into play. Next, the operation of the reducing pressure pressurizer (13) is switched to bring the inside of the cleaning tank (11) to a predetermined pressure, for example, atmospheric pressure or a predetermined pressurized state. As a result, the entire main surface of the wafer (1), including the inside of the trench (2), is uniformly wetted with the cleaning liquid (4). In this way, the cleaning liquid (4) is sufficiently spread into the trench (2), and cleaning is performed completely (FIG. 2 <<d>>).

After that, the cleaning liquid (4) is discharged from the drain port (18) and drying process is performed, or the wafer (1) is removed from the cleaning tank (18).
1), and drying processing is performed in another drying processing section. Wafers processed in this way (1
) is completed into a semiconductor device, the quality is improved,
You can get something highly reliable.

In the above embodiment, the process was carried out under reduced pressure up to the stage of controlling the wafer cooler (19) to melt the ice (3), but at the stage of supplying water vapor (6) into the cleaning tank (10). The cleaning liquid (4) may be at atmospheric pressure.Although water is used as an example in this case, the cleaning liquid (4) is not limited to this, and other liquids may be used as long as they have the property of easily dissolving water vapor (6). For example, alcohol or the like may be used, and the same effect as above can be achieved.

[Effects of the Invention] As described above, according to the present invention, a cooling means for cooling a semiconductor substrate is provided, the inside of the processing tree is brought into a reduced pressure state, and the water vapor generated by the water vapor generating means adheres to the four parts of the substrate. The cleaning is performed by cooling and forming ice, and the cleaning liquid supplied from the cleaning liquid supply means melts the ice. Therefore, sufficient cleaning is performed, the crystallinity is improved, and reliability is improved. The effect of obtaining superior results is shown below.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a schematic configuration of a cleaning device according to an embodiment of the present invention, and FIGS. 2(a) to 2(d) show four main parts formed on a substrate by the cleaning device shown in FIG. FIG. 3 is a cross-sectional view showing the cleaning process; FIG. 3 is a diagram schematically explaining the state in which ice in the recess is dissolved in water; FIG. FIG. 5 is a sectional view showing a conventional state in which a recess formed in a substrate is cleaned. In the figure, (1) is the wafer, (2) is the trench, and (3) is the wafer.
) is ice, (4) is cleaning liquid, <<6>> is water vapor, (11)
is a cleaning tank, 《l3) is a pressure reducer/pressurizer, (14) is a steam generator, (l9) is a wafer cooler, and % (20) is a change from ice to water. In each figure, the same symbols indicate the same or equivalent parts.

Claims (2)

[Claims] (1) Bring the processing tank in which the semiconductor substrates are housed to a reduced pressure state,
A method for cleaning a semiconductor substrate, wherein water vapor is supplied to the substrate being cooled to form ice on a main surface portion including a recess formed in the substrate, and then a cleaning liquid is supplied to the substrate to perform cleaning. (2) A sealable processing tank, provided within this processing tank,
A cooling means for cooling a semiconductor substrate placed in the processing tank, a water vapor generating means for supplying the substrate with water vapor that may adhere to a recess formed in the substrate, and a cleaning liquid capable of dissolving the water vapor. A semiconductor substrate cleaning apparatus comprising a cleaning liquid supply means for supplying the substrate, and a depressurization/pressurization means for reducing or pressurizing the inside of the processing tank.