JPH10270395A - Method for adjusting gas atmosphere in polishing/ cleaning process for wafer substrate and device for executing the method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve cleaning effect for reduced foreign substances sticking on surface, by polishing a surface while it is contacting to cleaning water, and adjusting gas atmosphere so that the gas used in the process may flow into a polishing process side while a abrasive liquid is contacting to the polished surface. SOLUTION: A finish-polishing top ring 8 falls while sucking a wafer substrate W from upper surface side, while a abrasive fabric is rotated together with a stool 9, and the lower surface of wafer substrate W is cut by synergetic effect of abrasive fabric and abrasive liquid. A water polishing/cleaning device top ring 14 sucks, holes the wafer substrate W, so the entire surface of wafer substrate W contacts to ultrapure water at always. When the wafer substrate W is moved from a finish/polishing part 2 side to a water polishing/cleaning part 1, it is transferred under water, so no gas on the finish/polishing part 2 side invades into the water polishing/cleaning part 1 side. During operation, an air conditioner 4b establishes gas flow from the water polishing/cleaning part 1 side to the finish/polishing part 2 side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for adjusting an atmosphere in a polishing and cleaning process for removing foreign substances on the surface of a wafer substrate and highly cleaning the surface, and an apparatus for performing the same, and more particularly, to a semiconductor ingot. The present invention relates to a method for adjusting the atmosphere when the surface of a wafer substrate cut out of a wafer is highly purified and an apparatus for performing the method.

[0002]

2. Description of the Related Art Generally, a wafer substrate obtained by slicing a silicon single crystal ingot to a certain thickness with a wire saw or an inner peripheral blade or the like has fine irregularities (or fine roughness, micro roughness) on its surface. Or the thickness of each wafer substrate is not uniform. Therefore, lapping is performed to flatten such fine irregularities, uniformize the depth of processing distortion, and uniformly adjust the thickness of the wafer substrate.

[0003] Further, the wafer substrate after lapping includes:
There is a work-strained layer generated by processing, and fine metal, polishing powder, particles such as silicon chips are attached to the work-strained layer, so etching is performed by a chemical corrosion method using strong acid and hydrofluoric acid. Then, the processing strain layer and the particles are removed.

[0004] After etching, the wafer substrate is subjected to alkali neutralization to remove the acid adhering to the surface, thoroughly washed with water, dried, and mirror-polished on one side. After polishing, the wafer substrate is immersed in a cleaning bath and washed with running water (pre-cleaning), and then the surface particles and metal are further removed in the final cleaning process, which has high gloss with chemical luster and no processing distortion. Is obtained.

In general, the cleanliness of the surface of a wafer substrate directly affects semiconductor device characteristics. If the cleanliness is reduced, it may cause a failure in forming a device pattern or adversely affect the electrical characteristics of the semiconductor device. Exert.

[0006] The decrease in the cleanliness of the wafer substrate surface is caused not only by fine irregularities (ie, fine roughness and micro roughness) on the wafer substrate surface, but also by particles (fine particles) adhering to the wafer substrate surface in each wafer processing step. , Metal impurities, and foreign substances such as organic substances.

Therefore, conventionally, the micro-roughness is improved in each of the above-mentioned steps, ie, mechanical polishing (lapping), chemical etching, and mirror polishing (polishing), and further, polishing is performed in a cleaning tank supplied with a large amount of cleaning liquid. Foreign substances adhering to the surface of the wafer substrate are removed by pre-cleaning in which the wafer substrate is immersed later and final cleaning in which the wafer substrate after pre-cleaning is chemically cleaned.

[0008]

However, the conventional method of cleaning a wafer substrate has the following problems. Cleaning must be performed for a long time in chemical etching or pre-cleaning in order to completely remove organic substances such as wax applied on the back surface of the wafer substrate and abrasives remaining on the surface during lapping and polishing, and it takes time. .

In chemical etching and pre-cleaning, a large amount of an acid-based chemical such as hydrochloric acid, hydrofluoric acid, or nitric acid, or an alkali-based chemical such as sodium hydroxide or ammonium hydroxide is used as a cleaning liquid. Thus, the surface of the wafer substrate is cleaned by a chemical reaction. Since the reaction temperature at this time is high and the chemical solution must be maintained at a high temperature,
Huge power is required and costly.

In addition, a large amount of chemical liquid comes out as a waste liquid, and this chemical liquid needs to be treated and then discarded because it causes environmental pollution. Therefore, a separate step for waste liquid treatment is only required. In addition, there is a problem that the cost for that is also high. This is particularly serious because the larger the diameter of the wafer is, the larger the amount of the required chemical liquid is.

Further, the chemical solution attached to the wafer substrate after the chemical etching and the pre-cleaning is removed by neutralizing and thoroughly cleaning with water. Is corroded and haze occurs.

In the pre-cleaning, the cleaning is performed by a method relying on the action of the water flow of the cleaning liquid to supply the cleaning liquid while the wafer substrate is immersed in the cleaning tank and the action of the chemical property of the cleaning liquid. Since a foreign substance is not forcibly removed by using a machine, it is difficult to reduce very small particles.

Further, foreign matter such as particles removed from the wafer substrate easily accumulates in the cleaning tank, and the foreign matter once separated from the surface of the wafer substrate adheres again by convection in the cleaning tank or remains in the cleaning tank. There is also a problem that it is difficult to completely remove the foreign matter on the surface of the wafer substrate due to the phenomenon that the foreign matter adheres to the surface. As described above, if final cleaning is performed in a state where foreign matter is attached to the surface of the wafer substrate, the cleaning efficiency is reduced, and there is a problem that a highly purified wafer substrate cannot be finally obtained.

In the pre-cleaning, since a large amount of cleaning liquid is used, there is a problem that the apparatus becomes large-scale and the manufacturing cost increases. In particular, the problem becomes more remarkable as the diameter of the wafer to be manufactured becomes larger.

In order to reduce these problems, by adopting a double-side polishing method for simultaneously polishing both surfaces of a wafer substrate in mirror polishing or the like, adhesion of organic substances such as wax used for fixing the wafer substrate can be prevented. To reduce the time for chemical etching and pre-cleaning, and to reduce the amount of chemical solution used.

However, if chemical etching and pre-cleaning are not performed, the work time for mirror polishing becomes long, and foreign matter remaining on the wafer substrate surface increases. Further, as a pretreatment for the final cleaning, foreign substances such as particles, organic substances, and metal impurities adhering to the wafer substrate at the time of finishing mirror polishing cannot be reduced. For this reason, the final cleaning must be performed while the foreign matter is adhered to the wafer substrate, resulting in a decrease in the cleaning efficiency in the final cleaning, and there is a problem that a highly purified wafer substrate cannot be manufactured.

In order to solve these problems, studies have been made on a water polishing step of buff polishing using only cleaning water after mirror polishing. According to this water polishing step, foreign substances such as particles, organic substances, and metal impurities adhering to the wafer substrate surface can be reduced without performing chemical etching or pre-cleaning. However, on the other hand, since the mechanical work is performed, the cleanliness of the gas atmosphere in the processing space becomes a problem.

As described above, the present invention provides a gas cleaning and polishing process for a wafer substrate to obtain a highly purified wafer substrate having an improved cleaning effect as compared with the conventional one, that is, with a reduced amount of foreign substances adhering to the surface. It is a main object to provide an atmosphere adjusting method and an apparatus for performing the adjusting method.

Another object of the present invention is to provide a method for adjusting a gas atmosphere in a polishing and cleaning process of a wafer substrate, which can always keep the cleanliness of a gas atmosphere in a processing space at the time of performing a water polishing process. It is an object to provide an apparatus for performing the adjustment method.

[0020]

In order to achieve the above object,
The invention according to claim 1 is a gas atmosphere adjusting method in a polishing and cleaning process of a wafer substrate having a plurality of different multi-stage polishing processes on the surface of the wafer substrate, wherein the surface of the wafer substrate is polished to a mirror surface. A first polishing step (mirror polishing step) of supplying a polishing liquid containing an abrasive to the surface of the wafer substrate and polishing (buffing) the polishing liquid in a state in which the polishing liquid is in contact with the polishing surface; In order to remove foreign substances on the surface of the wafer substrate or to improve fine roughness, the polishing means is not used on the surface of the wafer substrate by a polishing means different from that used in the first polishing step. A second polishing step (buffer cleaning step) in which only the cleaning water is supplied to the polishing surface and the polishing water is in contact with the cleaning water (buffing), and the second polishing step is performed after the first polishing step. Performing the second polishing step, wherein the second polishing step is performed. Adjusting the gas atmosphere used in each step such that the gas used in the first step flows into the first polishing step side unilaterally. I have.

Further, the present invention provides the gas atmosphere adjusting method, wherein the first polishing step (mirror polishing step) comprises a two-step buff polishing step of a rough polishing step and a precision finish polishing step. The second polishing step (water polishing cleaning step) between the rough polishing step and the precision finishing step.
Including those that perform

According to the present invention, the wafer substrate which has been mirror-polished in the first polishing step is subjected to water polishing in which the wafer substrate is brought into contact with the cleaning water in the second polishing step by another polishing means. Perform different types of polishing work. And the second
The gas used in the second polishing step is changed to the first polishing step by flowing the gas used in the first polishing step unilaterally into the first polishing step.
Is maintained in a gas atmosphere that is cleaner than in the polishing process described above.

The gas used in the second polishing step is used for the first polishing.
By flowing unilaterally to the polishing process side of
This prevents the flow of gas from the polishing step side to the second polishing step side. These are for efficiently using a gas to be used when performing a plurality of mechanical polishing processes in a predetermined gas atmosphere. That is, since the gas adjusted to a high degree of cleanliness in the second polishing step flows into the first polishing step side, the gas for individually supplying the gas to the first polishing step side to adjust the cleanliness level is high. The operation becomes unnecessary, and the gas atmosphere can be adjusted efficiently.

Further, particles such as silicon dust, polishing powder, and fine metal which are removed from the wafer substrate in the first polishing step and float in the gas atmosphere are mixed into the gas atmosphere in the second polishing step, and It is possible to prevent re-adhesion to the substrate, and to always maintain a gas atmosphere with high cleanliness. Therefore, the wafer substrate can be sent to the next step while keeping the cleanliness obtained by the water polishing.

That is, in the present invention, in the first polishing step,
Since polishing is performed using an abrasive or the like, fine particles such as an abrasive and polishing dust easily float in a gas atmosphere. On the other hand, in the second polishing step, polishing is performed without using an abrasive, so that scattering of particles into the gas atmosphere is significantly smaller than that in the first polishing step.

If these different polishing steps are performed in the same space, particles scattered in the gas atmosphere in the first polishing step may adhere to the wafer substrate during the second polishing step. This lowers the cleanliness of the wafer.

In the case of arranging these components in completely different spaces, it is necessary to supply the respective gas atmospheres individually. Therefore, equipment for that purpose must be provided in each space. No. This causes an increase in the amount of gas used and an increase in the size of the equipment, resulting in an increase in cost.

In the present invention, the gas used in the second polishing step is allowed to flow into the first polishing step in consideration of the cleanliness of the gas atmosphere required in each processing step.
The above-described reduction in the amount of gas used and the downsizing of the equipment are achieved, and at the same time, the efficiency is improved by reusing the gas.

The wafer substrate described in the present invention refers to a wafer substrate during or after multi-step mirror polishing using an abrasive material. Of course, the present invention refers to a wafer substrate after lapping or after processing. It can also be applied to the polishing and cleaning processing of a wafer substrate having a pattern, a wafer substrate with a pattern having undergone a device CMP process, and a wafer substrate having an oxide film having undergone an SOI process.

In this case, the gas used in the second polishing step is unidirectionally flowed into the polishing step (for example, the lapping step) side of the previous stage of the second polishing step (water polishing and cleaning step). Adjust the gas atmosphere used in the step.

In the first polishing step, the cleanliness of the gas atmosphere is set to such a level as not to increase the number of particles generated in the polishing processing step and floating in the gas atmosphere or higher, and the second polishing step is performed at the second polishing step. In the polishing step, since functional water is used as cleaning water, a gas such as an inert gas such as nitrogen gas, helium, or argon is used to prevent suspended matters such as dust and dirt from being taken into the functional water. Used as a high level of cleanliness.

The high cleanliness level means, for example, air from which suspended matter has been removed by a filter device or the like.
A level composed of only a chemically stable gas (ie, an inert gas) such as carbon dioxide gas or nitrogen gas, in addition to rare gases such as argon and helium.

These highly purified gases are constantly supplied to the second polishing step side, and the gases used here are allowed to flow into the first polishing step side so that the gases used can be shared. In addition, the cleanliness level required in each process can be maintained.

The second polishing step (water polishing / cleaning step) of the present invention is a step performed for the purpose of cleaning the surface (polished surface) of the wafer substrate to a high degree of cleanliness in the mirror polishing step. This removes residual abrasives such as chemicals used in the process, and foreign matters such as particles, organic substances, and metal impurities adhered to the surface during the processing in the previous step or during the transfer of the wafer substrate.

Here, "polishing the polished surface in contact with the cleaning water" in the second polishing step means that only the cleaning water is interposed between the surface of the wafer substrate to be polished and the polishing means. Polishing the substrate surface, for example, can be achieved by polishing the wafer substrate while constantly spraying only the cleaning water on the wafer substrate, and using the same polishing means after the polishing process using the polishing material. The polishing is not performed by supplying only the cleaning water. In other words,
In the second polishing step, the surface of the wafer substrate can be polished by the polishing means, and at the same time, can be cleaned with cleaning water.

The polishing means is different from the polishing in the lapping step and the mirror polishing step, and its configuration is not particularly limited as long as it can polish the wafer substrate surface. For example, there is a mechanical polishing means such as a buff polishing member for performing a buff polishing using a platen or the like.

The polishing in the second polishing step (water polishing and cleaning step) is performed by using only cleaning water without using an abrasive. As a result, there is no possibility that the abrasive is adhered to the surface of the semiconductor wafer and the surface is contaminated. Furthermore, since not only mere cleaning but also polishing is performed at the same time, there is an effect of further improving the micro roughness.

Therefore, not only can the foreign matter be forcibly removed from the surface of the wafer substrate by the polishing means and the washing water, but also the foreign matter floating in the gas atmosphere adheres to the surface of the wafer substrate. Because it is difficult to do
In the conventional cleaning method, foreign matters such as small particles that cannot be removed can be removed and the state can be maintained.

Second polishing step (water polishing and cleaning step)
In the above, the foreign matter once removed from the wafer substrate is forcibly removed by the polishing means and does not accumulate on the surface of the wafer substrate, so that the foreign matter may remain in the cleaning water and reattach to the wafer substrate surface. Absent.

Even if these foreign matters are scattered, they are ventilated (flowed) to the first polishing step side, so that the adhesion of the foreign matters from the gas atmosphere is reduced. Since the cleanliness required for the gas atmosphere in the first polishing step is lower than that in the first polishing step, there is no substantial influence even if the gas flowing from the first polishing step is used.

That is, for example, in a case where the present invention is applied to cleaning after mirror polishing, the wafer substrate that has been mirror-polished in the first polishing step is polished in a second polishing step while being in contact with cleaning water. When performing mechanical cleaning by polishing together with quasi-chemical cleaning of the cleaning water (that is, performing water polishing), it is possible to optimally maintain the cleanliness of the gas atmosphere in the processing space. Therefore, there is an advantage that water polishing can be performed in an ideal environment.

Of course, since the wafer substrate which has been mirror-polished in the first polishing step is cleaned by water polishing performed in an ideal environment, there is no need for chemical etching or pre-cleaning using a strong acid, alkali or the like as in the prior art. In addition, there is an advantage that problems due to these do not occur.

Here, as the cleaning water used in the second polishing step, for example, LDO water (low dissolved oxygen water),
CO ₂ water, megasonic (MS) irradiating ultra pure water, ozone added ultrapure water, electrolytic ionic water (anode water, cathode water) As such, functional water obtained by imparting some function to the ultrapure water. Of course, a plurality of these may be selected and used in order as washing water.

In other words, since functional water obtained by imparting some function to ultrapure water is used as cleaning water, acid remaining on the surface of the wafer substrate after etching as in conventional chemical etching and pre-cleaning causes the wafer surface to be cleaned. It has corroded,
There is no problem caused by etching, such as a large amount of strong acid coming out as a waste liquid.

Next, according to the second aspect of the present invention, in the polishing and cleaning apparatus having a plurality of different multi-stage polishing means for polishing the surface of the wafer substrate, the surface of the wafer substrate is mirror-polished. A first polishing means (mirror polishing means) for supplying a polishing liquid containing an abrasive to the surface of the wafer substrate and polishing the polishing liquid while the polishing liquid is in contact with the polishing surface; and a first polishing means. A first shielding means for shutting off the processing space from the outside and maintaining the processing space in a predetermined gas atmosphere; and a first shielding means for removing foreign substances on the surface of the wafer substrate and improving fine roughness and the like. A second polishing means for supplying only cleaning water to the surface of the wafer substrate without using an abrasive by using a polishing means different from that used in the polishing step, and polishing the wafer surface while the cleaning water is in contact with the polishing surface; Polishing means (water polishing means)
A second shielding means for shutting off the second polishing means from the outside, and maintaining a processing space in a gas atmosphere of the same component as the gas used in the first shielding means; The two spaces shielded from the outside by the second shielding means communicate with each other, and one side from the space side shielded from the outside by the second shielding means to the space side shielded from the outside by the first shielding means. And a gas atmosphere adjusting means for causing the gas to flow in.

That is, the present invention is an apparatus for carrying out the invention of claim 1, wherein a first polishing means (hereinafter, referred to as a first space) is shielded by a first shielding means. The second polishing means (water polishing means) is stored in a space shielded by the second shielding means (hereinafter referred to as a second space), and the gas atmosphere adjusting means is stored in the space. This is to allow the gas to flow unilaterally from the second space side to the first space side.

That is, the apparatus of the present invention uses a first polishing means for performing a mirror finish on the surface of a wafer substrate using a polishing liquid containing an abrasive and functional water containing no abrasive as cleaning water. A second polishing means for polishing the surface of the wafer substrate with water, and a first shielding means and a second shielding means for shielding each means from the outside air.

The surface of the wafer substrate conveyed to the first polishing means has an atomic level surface roughness (microroughness) such as ripple and haze. Particles such as powder and silicon dust are attached. Therefore, the first shielding means shields the first polishing means from the outside air and keeps the first space at a level at which these particles do not increase.

Further, a lower level of micro-roughness and extremely minute particles adhere to the surface of the wafer substrate mirror-polished by the first polishing means. The second polishing means further removes them by water polishing. However, the functional water used as the cleaning water at this time is easily contaminated by suspended matters such as dust and dirt. And the second space is kept at a level at which floating substances such as dust and dirt are completely removed.

Further, in the present invention, the gas atmosphere adjusting means unilaterally flows the gas from the second space side to the first space side. That is, since the functional water is used as the cleaning water in the second polishing step, it is necessary to fill the second space with a highly purified gas to a level at which the cleaning water is not contaminated.

Therefore, by allowing the gas in the second space to flow unilaterally into the first space, the gas having a high degree of cleanliness in the second space flows into the first space. The cleanliness can be equal to or higher than the gas atmosphere in the two spaces. Furthermore, an independent or separate device and operation for filling the first space with a gas having a high cleanliness level are not required, and the gas atmosphere can be adjusted efficiently.

Accordingly, impurities such as dust and dirt floating in the first space enter the second space, are taken into the washing water, and adhere to the wafer substrate during or before or after the processing of the wafer substrate by the second polishing means. Without adhering, it can be sent to the next step while maintaining the cleanliness obtained by water polishing.

Here, the gas supply means in the present invention supplies the gas to be used to the second shielding means while maintaining a high degree of cleanliness, and a part of the gas is simultaneously introduced into the first shielding means. You may. That is, the gas supplied into the second shielding means is a highly purified gas, and the gas atmosphere adjusting means functions so that the gas used in the first shielding means does not flow into the second shielding means. .

The gas used in the first or second shielding means is ventilated to the outside, and the particles scattered in the gas or a separately provided removing means (not described in detail here)
And so on. Further, the highly purified gas may be supplied again into the second shielding means by the gas atmosphere adjusting means.

The gas atmosphere adjusting means of the present invention includes, for example, a gas inlet provided on the wafer substrate outlet side of the first space, and a cleaner for cleaning air connected to the gas inlet via an on-off valve. Equipment and gas tank filled with inert gas such as nitrogen gas, helium, argon (gas supply means)
And a mechanism provided with a through-hole provided in a wall surface separating the first space and the second space, and a fan member provided in the through-hole and sending out air from the second space toward the first space.

As another example, a gas inlet opening only to the second space side and a through hole penetrating the first space and the second space are provided on a separation wall separating the first space and the second space. A purifier for purifying air connected to a gas inlet via an on-off valve, a gas tank (gas supply means) filled with an inert gas such as nitrogen gas, helium, argon, etc .; And a fan member for sending air from the two spaces toward the first space.

In addition, in addition to the above configuration, a configuration may be adopted in which a new gas is supplied not only to the second space but also to the first space. In this case, a gas inlet is also provided in the first space, and is connected to a gas tank (gas supply means) via an on-off valve. At this time,
The gas atmosphere adjusting means adjusts the flow rate of a newly supplied gas from the outside so as not to obstruct the flow of air from the second space to the first space.

By adopting such a configuration, it is not necessary to separately provide means for adjusting the atmosphere in each space, so that not only the cost for manufacturing the device can be reduced, but also the configuration of the device can be reduced. Can be easy.

The functional water, which is the cleaning water used by the second polishing means, may be, for example, LDO water (low-dissolved oxygen water), CO ₂ water, Functional water obtained by imparting some function to functional water such as sonic (MS) irradiated ultrapure water, ozone-added ultrapure water, and electrolytic ionic water (anode water, cathode water). Of course, a plurality of these may be selected and used in order as washing water.

Further, according to a third aspect of the present invention, there is provided the gas atmosphere adjusting apparatus in the polishing and cleaning processing of the wafer substrate according to the second aspect, further comprising a third shielding means for shutting off the gas atmosphere adjusting apparatus from the outside. The first and second shielding means are characterized by being formed in spaces independent of each other by a dividing wall provided inside the third shielding means.

That is, the entire gas atmosphere adjusting device is
Is shielded from the outside by the shielding means (for example, a chamber), and is divided into two independent spaces (that is, the first space and the second space) by the dividing wall provided inside the third shielding means.
Is formed, the polishing and cleaning of the wafer substrate can be performed by an integrated polishing and cleaning apparatus that is integrated, so that the gas atmosphere adjustment of the first space and the second space can be performed by a device with a relatively simple configuration.

According to a fourth aspect of the present invention, in the gas atmosphere adjusting apparatus for polishing and cleaning a wafer substrate according to the third aspect, the gas atmosphere adjusting means is provided on the partition wall. It is assumed that. That is, the gas atmosphere adjusting means is replaced with a third shielding means (chamber).
By storing it in a dividing wall provided inside the device, a compact device can be obtained. Further, the gas atmosphere adjusting means may be a duct or the like communicating with the dividing wall.

[0063]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory view showing one embodiment of a wafer polishing and cleaning apparatus of the present invention.

In this polishing and cleaning apparatus, a mirror polishing apparatus, which is a first polishing means for receiving a wafer in a state where a silicon igot is cut into a plurality of pieces by a wire saw or an inner peripheral blade and subjected to lapping, and performs polishing, is housed therein. And a water polishing / cleaning unit 1 in which a water polishing / cleaning apparatus, which is a second polishing means for receiving the polished wafer and polishing and cleaning the surface, is housed.

The finish polishing section 2 and the water polishing / cleaning section 1 are isolated from the outside air by a chamber 30 which is a third shielding means, and are first shielded by a partition wall 3 which is a partition wall provided inside. The means and the second shielding means are independently separated from each other. The respective chambers of the second shielding means in which the finish polishing unit 2 is sealed and the first shielding means in which the water polishing / cleaning unit 1 is sealed are filled with nitrogen gas constituting the gas atmosphere of the processing space. . In this partition 3,
First and second air conditioners 4 constituting gas atmosphere adjusting means for always keeping each room clean.
a, 4b are provided.

The first air conditioner 4a comprises a fan member and the like connected to a nitrogen tank T constituting gas supply means, and as shown by an arrow A in FIG. , A highly purified nitrogen gas is introduced from a nitrogen tank T. Here, a new gas is supplied to the second space Mami, but it may be configured to supply the new gas to the first space at the same time.

The second air conditioner 4b is provided in the partition wall 3 between the finish polishing section 2 as the first space and the water polishing and cleaning section 1 as the second space. Is provided with a fan member (not shown) installed in the apparatus. This fan member draws nitrogen gas from the water polishing / cleaning unit 1 into the finish polishing unit 2 as indicated by an arrow B in the drawing.

The wafer substrate W after the primary polishing such as polishing is introduced into the finish polishing section 2 through a preliminary chamber (not shown) while being held by the holder 5a. In the finish polishing section 2, the wafer loader 6 takes out the wafer substrate W from the holder 5a and places the wafer substrate W on the transfer table 7.

When the wafer substrate W is placed on the transfer table 7, the finish polishing top ring 8 of the first polishing means sucks the wafer substrate W from the upper surface side and lifts the wafer substrate W from the transfer table 7. It moves on the board 9.

The finish polishing surface plate 9 is rotated at a constant speed by a motor (not shown) with the center as a rotation center.
A polishing cloth for mirror polishing is laid on the surface plate 9. Above the surface plate 9, a polishing liquid supply nozzle 9a provided in the polishing apparatus and supplying a polishing liquid containing an abrasive to the surface plate 9 is arranged.

The finish polishing top ring 8 descends while sucking the wafer substrate W from the upper surface side, and presses the lower surface of the wafer substrate W against the polishing cloth. Since the polishing cloth rotates together with the platen 9, the rotation causes the lower surface of the wafer substrate W to be shaved by the synergistic action of the polishing cloth and the polishing liquid.

The top ring for finish polishing 8 gradually moves in the direction of arrow C in the figure while the lower surface of the wafer substrate W is pressed against the polishing cloth to polish the lower surface of the wafer substrate W for 10 minutes. Thereafter, the top ring 8 for finish polishing lifts the wafer substrate W while sucking the wafer substrate W from the upper surface side, and moves toward the underwater transfer device 10.

The underwater transport device 10 is provided over the finish polishing section 2 and the water polishing / cleaning section 1, and is provided with a water tank 11 filled with rinsing water, and immersed in the rinsing water in the water tank 11. A plurality of substantially cylindrical roll brushes 12, a jet nozzle (not shown) for flowing rinsing water in a direction opposite to the traveling direction of the wafer substrate W, and a motor (not shown) for rotating the roll brushes 12; It has.

The individual roll brushes 12 are mounted on the wafer substrate W
Are arranged in a direction perpendicular to the traveling direction of the wafer substrate W and are respectively arranged along the traveling direction of the wafer substrate W. The wafer substrate W is rotated in the same direction by the power of a motor (not shown), and is transported toward the water polishing / cleaning unit 1 side.

When the wafer substrate W is placed on the plurality of roll brushes 12, the finish polishing top ring 8 stops sucking and transfers the wafer substrate W to the underwater transport device 10. The delivered wafer substrate W moves underwater on the roll brush 12 with the rotation of the brush, and is conveyed toward the water polishing and cleaning unit 1 side.

When the wafer substrate W moves from the finish polishing section 2 to the water polishing / cleaning section 1, the wafer substrate W is transported in water. Do not enter part 1. During these operations, the second air conditioner 4b always forms a flow of nitrogen gas from the water polishing / cleaning unit 1 to the finish polishing unit 2.

A wafer transfer tank 13 is connected to the water polishing and cleaning unit 1 side of the underwater transfer device 10, and the wafer substrate W transferred on the roll brush 12 is transferred to the wafer transfer tank 13 while being immersed in water. It is.

The water polishing / cleaning unit 1 houses a water polishing / cleaning device, and a first air conditioner 4a is always provided in the second shielding means in the space where the water polishing / cleaning unit 1 is disposed. It supplies clean nitrogen gas.

In such an atmosphere, the wafer substrate W delivered to the wafer delivery tank 13 is suction-held from the upper surface side by the water polishing / cleaning top ring 14 and pulled up. At this time, ultrapure water is always supplied to the surface by a shower (not shown). Therefore, even when the top ring for the water polishing and cleaning apparatus sucks and holds the wafer substrate W, the entire surface of the wafer substrate W is always in contact with the ultrapure water. Accordingly, the wafer substrate W is transported in a wet state, is suction-held by the water polishing and cleaning apparatus top ring 14, and is transferred onto the water polishing and cleaning platen 15.

The surface plate 15 for water polishing and cleaning is rotated at a constant speed by a motor (not shown) about the center of rotation as a center of rotation, and a polishing cloth for cleaning and polishing is laid on the surface plate.
Above the platen 15, two nozzles 14a and 14b for supplying cleaning water are arranged.

One of these nozzles 14a and 14b ejects LDO water (low-dissolved oxygen water) as washing water, and the other 14b comprises a megasonic slit line having a plurality of injection ports provided with megasonic oscillators. , Blast megasonic irradiated ultrapure water.

While supplying cleaning water, the top ring for the water polishing / cleaning apparatus descends while sucking the wafer substrate W from the upper surface side, and presses the lower surface of the wafer substrate W against the polishing cloth.
Since the polishing cloth rotates together with the platen 15, the lower surface of the wafer substrate W is mechanically polished and cleaned by this rotation. At this time, separately from the washing water injection nozzle of the washing device top ring, two nozzles 14a, 14a,
Cleaning water is supplied from 14b.

Then, the two nozzles 14a, 14b
Nozzle 1 that jets LDO water (low dissolved oxygen water)
The LDO water from the nozzle 4a is initially supplied to the platen 15, and after 3 minutes, the supply of the LDO water from the nozzle 14a is stopped, and at the same time, megasonic irradiation ultrapure water starts to spray from the nozzle 14b, and the cleaning is performed. The water switches from LDO water to megasonic irradiated ultrapure water.

After a lapse of 3 to 5 minutes, the top ring for the water polishing / cleaning apparatus rises while sucking the wafer substrate W from the upper surface side, pulls the wafer substrate W away from the platen 15, and receives the wafer substrate W from the receiving side of the underwater slider device 16. Go to

The underwater slider device 16 has a slide structure in which the wafer substrate receiving side 16a is higher than the wafer substrate transfer side 16b.
Since a is always supplied with cleaning water from a cleaning water injection nozzle (not shown), the cleaning water always flows down from the wafer substrate receiving side 16a toward the transfer side 16b.

When the top ring 14 for the water polishing / cleaning device places the wafer substrate W on the wafer substrate receiving side 16a of the underwater slider device 16, the wafer substrate W flows down to the wafer substrate transfer side 16b together with the cleaning water. The holder 5b is disposed on the wafer substrate transfer side 16b, and holds the wafer substrate W flowing with the cleaning water in contact with the cleaning water.

The holder 5b holds the wafer substrate W in contact with the cleaning water until the final cleaning step after the completion of the water polishing (not described in detail here), and immerses the wafer substrate W in water. The wafer is transported to the next cleaning step, which is the next step.

As described above, of the two air conditioners, the first air conditioner 4a sequentially introduces new nitrogen gas into the water polishing / cleaning unit 1, while the second air conditioner 4b uses the fan member to turn the water polishing / cleaning unit 1 side. Is forcibly drawn into the finish polishing section 2 so that the nitrogen gas unilaterally flows into the finish polishing section 2 from the water polishing / cleaning section 1 side. It is not limited to this configuration.

For example, each of the inside of the water polishing / cleaning section 1 and the inside of the finish polishing section 2 is provided with a pressure control means for controlling the pressure in each space, and an insertion hole is formed in the partition wall 3 for separating the two spaces. A configuration is provided in which the nitrogen gas flows unilaterally into the finish polishing unit 2 from the water polishing / cleaning unit 1 side due to a pressure difference by maintaining the inside of the water polishing / cleaning unit 1 at a higher pressure than the inside of the finish polishing unit 2. It is also possible to do.

Although not shown, a duct is provided on the partition wall of the first shielding means as an exhaust means for exhausting the gas used in the processing space. That is,
During processing in the first shielding means, fine foreign substances such as particles are scattered and float in the gas atmosphere (floating foreign substances).
However, these increase as the processing time elapses. For this reason, exhaust means such as a duct is provided, and these suspended foreign substances are discharged by ventilating through the duct, thereby maintaining the cleanliness of the gas atmosphere in the first space.

Of course, the gas used in the second space flows into the first space, but the foreign matter contained in this gas is much smaller than the amount of foreign matter generated in the first space. There is almost no effect on the cleanliness in the first space.

Conversely, if these two processing spaces are integrated, no adverse effect on the water polishing / cleaning step can be measured. Further, in order to separately supply, adjust, and exhaust gas separately, the amount of gas used is greatly increased, and individual equipment is required, which is inefficient.

[0093]

As described above, according to the present invention, the gas used in the second polishing step is caused to flow unilaterally into the first polishing step, thereby achieving high cleanliness in the second polishing step. Since the adjusted gas flows into the first polishing step, the gas to be used can be shared, and the operation for adjusting the gas in the first polishing step to a high degree of cleanliness becomes unnecessary, so that the gas is efficiently used. Adjustment of the gas atmosphere can be performed.

Further, particles such as silicon dust, polishing powder, and fine metal, which are removed from the wafer substrate in the first polishing step and float in the gas atmosphere, are mixed in the gas atmosphere in the second polishing step, and It is possible to prevent re-adhesion to the substrate, and to always maintain a gas atmosphere with high cleanliness. Therefore, the wafer substrate can be sent to the next step while keeping the cleanliness obtained by the water polishing.

In other words, the surface of the wafer substrate can not only be forcibly removed from the surface of the wafer substrate by polishing by the polishing means and cleaning water, but also the foreign material floating in the gas atmosphere adheres to the surface of the wafer substrate. Therefore, foreign substances such as small particles that cannot be removed by the conventional cleaning method can be removed, and the state can be maintained.

Second polishing step (water polishing and cleaning step)
In the above, the foreign matter once removed from the wafer substrate is forcibly removed by the polishing means and does not accumulate on the surface of the wafer substrate. Absent.

For example, in the case where the present invention is applied to cleaning after mirror polishing, when the mirror-polished wafer substrate is polished with water, the cleanliness of the gas atmosphere in the processing space can be optimally maintained. Can be performed in an ideal environment.

Of course, since the wafer substrate which has been mirror-polished in the first polishing step is cleaned by water polishing performed in an ideal environment, conventional chemical etching using a strong acid or alkali or pre-cleaning is not required. There is also an advantage that the problem due to the above does not occur.

Further, the apparatus as a whole is smaller than the conventional apparatus, and the wafer manufacturing cost can be reduced.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing one embodiment of a wafer polishing and cleaning apparatus of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Water polishing washing part 2 Finish polishing part 3 Partition wall 4a, 4b Air conditioner 5a, 5b Holder 6 Wafer loader 7 Transfer stand 8 Finish polishing top ring 9 Finish polishing surface plate 9a Polishing liquid supply nozzle 10 Underwater transport device 11 Water tank 12 roll Brush 13 Wafer delivery tank 14 Top ring for water polishing and cleaning 14a, 14b Nozzle 15 Surface plate for water polishing and cleaning 16 Underwater slider device 16a Wafer substrate receiving side 16b Wafer substrate transfer side 30 Chamber W Wafer substrate T Nitrogen tank

Continued on the front page (72) Inventor Minami Minami 555 Nakanotani, Annaka-shi, Gunma 1 Inside Super Silicon Laboratories, Inc.

Claims (4)

[Claims] 1. A method for adjusting a gas atmosphere in a polishing and cleaning process of a wafer substrate having a plurality of different multi-stage polishing steps on the surface of the wafer substrate, the method comprising: A first polishing step of supplying a polishing liquid containing an abrasive to the surface of the wafer substrate and polishing the polishing liquid in a state where the polishing liquid is in contact with the polishing surface; In order to improve the fine roughness, etc., only cleaning water is supplied to the surface of the wafer substrate without using an abrasive by a polishing means different from that used in the first polishing step. And a second polishing step of polishing in a state in which the cleaning water is in contact with the cleaning water, wherein the second polishing step is performed after the first polishing step, and is used in the second polishing step. Gas flows unilaterally to the first polishing process side. As to the gas atmosphere adjusting method in the polishing cleaning of the wafer substrate, characterized by adjusting the gas atmosphere used in each step. 2. A polishing and cleaning apparatus having a plurality of different multi-stage polishing means for polishing the surface of a wafer substrate. In order to polish the surface of the wafer substrate to a mirror surface, an abrasive is applied to the surface of the wafer substrate. A first polishing means for supplying a polishing liquid containing the following, and polishing in a state in which the polishing liquid is in contact with the polishing surface; and a processing space for the first polishing means, which is cut off from the outside, is predetermined. A first shielding means for maintaining a gas atmosphere, and a polishing means different from that used in the first polishing step for removing foreign substances on the surface of the wafer substrate and improving fine roughness, etc., A second polishing means for supplying only the cleaning water to the surface of the wafer substrate without using an abrasive, and polishing in a state where the cleaning water is in contact with the polishing surface; and shutting off the second polishing means from the outside Then, the processing space is referred to as the first shielding hand. A second shielding means for maintaining a gas atmosphere of the same component as that of the gas used in the above, and connecting the respective spaces shielded from the outside by the first and second shielding means to each other, and the second shielding means Gas atmosphere adjusting means for allowing the gas to flow unilaterally from the space side cut off from the outside by the first shielding means to the space side cut off from the outside by the first shielding means. Gas atmosphere adjusting device in polishing and cleaning processing. 3. A third shielding means for shutting off the gas atmosphere adjusting device from the outside, wherein the first and second shielding means are provided by a dividing wall provided inside the third shielding means. 3. The gas atmosphere adjusting apparatus according to claim 2, wherein the gas atmosphere adjusting apparatuses are configured to be independent of each other. 4. The gas atmosphere adjusting apparatus according to claim 3, wherein the gas atmosphere adjusting means is provided on the partition wall.