Apparatus of processing semiconductor substrate

An apparatus of processing a semiconductor substrate include a chuck, a holder, a liquid supplying system and a positive pressure unit. The chuck has a principal surface and at least a hole formed thereon. The holder is capable of holding a semiconductor substrate at a position above the principal surface. The liquid supplying system is configured to provide a liquid film onto the principal surface through the hole. The positive pressure unit is configured for providing a gas flow to a space over the chuck. A method of processing a semiconductor substrate is disclosed herein as well.

BACKGROUND

The semiconductor integrated circuit (IC) industry has experienced rapid growth. Technological progress in IC manufacture has produced several generations of ICs, and each generation fabricates smaller and more complex circuits than the previous generation. Currently, the semiconductor industry has progressed into nanometer technology nodes for higher device density and better electrical performance, and three-dimensional designs, such as fin-like field effect transistors (FinFETs) are employed. Cleaning processes and wet etching processes are important in manufacturing ICs with nanometer scale features. A variety of cleaning apparatuses and wet etching apparatuses have be proposed by tool vendors, but conventional techniques have not been entirely satisfactory in all respects.

DETAILED DESCRIPTION

Cleaning and/or wet etching processes are important for manufacturing semiconductor integrated circuits (ICs). Generally, a semiconductor substrate such as for example a silicon wafer has a back surfaces and a device surface on which semiconductor devices are formed. In some cleaning and/or wet etching processes, it is desired that the cleaning or etching effects occur only on a single surface of the semiconductor substrate (i.e. processing surface), whereas the other surface (i.e. non-processing surface) is undesired to be affected by the working mediums such as for example cleaning and/or etching liquids. However, in conventional cleaning and/or wet etching apparatuses, the working mediums is inevitably splashed or moved onto the non-processing surface (also known as “backwash”), and leading to some problems. The conventional cleaning and/or wet etching tools can not promise the non-processing surface being absolutely free of the working mediums. One approach to resolve this problem is to form a protective layer covering the non-processing surface of the semiconductor substrate. This approach is cost-ineffective. Moreover, some nanometer structures such as for example the fin features of FinFETs are possibly broken when using conventional cleaning and/or wet etching apparatuses to manufacture modern ICs.

The present disclosure relates generally to an apparatus of processing a semiconductor substrate and a method of processing a semiconductor substrate. According to various embodiments of the present disclosure, the apparatus and method disclosed herein can reliably promise the non-processing surface being free of the working mediums. Furthermore, the apparatus and method disclosed herein resolve the broken issue of nanometer structures in the cleaning processes and/or wet etching processes.

FIG. 1is a cross-sectional view schematically illustrating an apparatus100of processing a semiconductor substrate according to various embodiments of the present disclosure. The apparatus100includes a chuck110, holder120, a liquid supplying system140and a positive pressure unit150.

The chuck110serves as a platform on which processes are performed. Specifically, the chuck110has a principal surface110A and one or more holes112formed thereon. In some embodiments, the principal surface110A of the chuck110extends in a substantially horizontal direction. The area or the size of the chuck110may be varied, depending upon the size of the semiconductor substrate to be processed. In some embodiments, a number of holes112are formed on the principal surface110A. Each of the holes112has an outlet on the principal surface110A, and therefore working mediums such as etching chemicals and cleaning liquid may be provided onto the principal surface110A through the holes112. In specifics, each of the holes112is connected to the liquid supplying system140, and the working mediums may be supplied to the principal surface110A of the chuck110. Accordingly, various processes may be carried out over the principal surface110A of the chuck110.

The liquid supplying system140is configured to provide a liquid film142onto the principal surface110A through the hole(s)112of the chuck110. The liquid supplying system140includes a liquid supplier144which is connected to one or more holes112and supplies liquid to the principal surface110A through the hole(s)120of the chuck110. The supplied liquid flows on the principal surface110A and thus forming a liquid film142flowing on the principal surface110A of the chuck110. In some embodiments, the liquid supplying system140includes a number of liquid suppliers such as liquid suppliers144,144A and144B. The liquid suppliers144,144A,144B are connected to one or more holes112and supply different materials or chemicals to the principal surface110A. For example, the liquid suppliers144,144A,144B may supply etching chemicals and/or cleaning solutions to the principal surface110A, and therefore the liquid film142may be an etching liquid film or a cleaning liquid film. In yet some embodiments, the liquid supplying system140further includes a distributor146which is interconnected between the holes112and the liquid suppliers144,144A,144B. The materials or chemicals from the liquid suppliers144,144A and144B are reliably mixed in the distributor146and then are distributed and transported to the holes112.

The holder120is disposed to hold a semiconductor substrate130at a position above the principal surface110A of the chuck110. Any type of wafer holders known in the art may be used in the present disclosure. In some embodiments, the holder120may clamp the edge of the semiconductor substrate130, and is moveable in a vertical direction. For example, the holder120may be positioned at a relatively high position when receiving the semiconductor substrate130. And then, the semiconductor substrate130may be moved downwards with the holder120to a relatively low position to carry out some processes such as for examples etching processes and/or cleaning processes. In some embodiments, the holder120may be programmably controlled so that the gap134between the semiconductor substrate130and the principal surface110A may be varied during the process time. In yet some embodiments, the holder120may be combined with a robot, and may pick up the semiconductor substrate130from a cassette and further support it at a desired position above the principal surface110A of the chuck110. The chuck110may be formed of a material such as for example stainless steel, titanium alloy, aluminum alloy, or the like.

The semiconductor substrate130is supported at a level above the principal surface110A of the chuck110by the holder120when the apparatus100is under operation. Further, the semiconductor substrate130has a first surface131to be processed and a second surface132opposite to the first surface131. When the apparatus100is under operation, the first surface131of the semiconductor substrate130faces down and opposite to the principal surface110A of the chuck110. The first surface131is spaced apart from the principal surface110A by the gap134during the process time, and therefore the liquid film142may flow in the gap134and in contact with the first surface131. In this way, the liquid film142may interact with the first surface131so to implement certain effects on the first surface131, for example etching and/or cleaning the first surface131. The liquid film142drains off the gap134from the edge of the chuck110.

In various embodiments, the semiconductor substrate130is not spun or revolved during the process time, and therefore the apparatus disclosed herein is advantageous to process a large-size substrate because the substrate is in a static condition. In conventional techniques, the semiconductor substrate is rotated during the process time, and unfavorably leads to bending of the semiconductor substrate. Accordingly, the apparatus100provided herein is suitable for processing large-size substrates such as for example 18-inch wafers or larger. Nevertheless, the present disclosure is not limited to specific semiconductor substrates, and any semiconductor substrate may be used in the present disclosure.

The positive pressure unit150is configured to provide a gas flow152to a space over the chuck110. When the apparatus100is under operation, the gas flow152is supplied to the second surface132of the semiconductor substrate130, and the gas flow152blows over the edge of the second surface132, and then leaves the second surface132of the semiconductor substrate130. In some embodiments, the positive pressure unit150includes a cover154and a first gas supplier156connecting to the cover154. When the apparatus100is under operation, the cover154is moved to a position above the semiconductor substrate130, covering the semiconductor substrate130. The first gas supplier156supplies the gas flow152into the space between the cover154and the second surface132of the semiconductor substrate130, and a positive pressure space158is therefore created over the second surface132of the semiconductor substrate130. The gas supplied by the first gas supplier156flows out of the space158from the edge of the semiconductor substrate130. In some examples, the gas flow152includes nitrogen gas, air or other suitable gas.

It is noted that the problems of “backwash” are effectively resolved by the arrangement of the positive pressure unit150, the semiconductor substrate130and the chuck110disclosed herein. First, the semiconductor substrate130is arranged above the liquid film142which serves as the working medium. When the liquid film142leaves the principal surface110A of the chuck110, the outflow liquid148substantially flows downwards due to the gravity effect, and this considerably decreases the possibility of “backwash”. Second, the gas supplied from the positive pressure unit150create a positive pressure space158on the second surface132of the semiconductor substrate130, and the positive pressure space158prevents the outflow liquid148from splashing onto the second surface132of the semiconductor substrate130. Furthermore, the gas flow152blowing over the edge of the semiconductor substrate130directs the outflow liquid148to flow downwards. Accordingly, the second surface132of the semiconductor substrate130is free of any liquid splashed or moved from liquid film142, and the problems regarding “backwash” are effectively resolved in various embodiments of the present disclosure.

In some embodiments, the apparatus100further includes a drainage unit160disposed adjacent to an edge of the chuck110. The drainage unit160is configured to drain liquid148from the edge of the chuck110. In some examples, the drainage unit160includes a first suction head162neighboring the edge of the chuck110. The first suction head162is positioned at a level between the first surface131of the semiconductor substrate130and the principal surface110A of the chuck110, and the outflow liquid148is sucked into the first suction head162. Significantly, the first suction head162and gas flow152blowing over the edge of the semiconductor substrate130aconstitute a gas stream at the edge of the semiconductor substrate130and the edge of the liquid film142. The constituted gas stream directs the outflow liquid148into the first suction head162, and effectively prevents the liquid148from splashing onto the second surface132of the semiconductor substrate130. In yet some examples, the drainage unit160further includes a second suction head164positioned at a level below the principal surface110A. The second suction head164may suck remained liquid under the first suction head162.

In some embodiments, the apparatus100further includes a nebulizer170connected to the hole(s)112. The nebulizer170is configured to supply a spray or droplets to the first surface131of the semiconductor substrate130through the hole(s)112of the chuck110. The spray or droplets supplied from the nebulizer170is for the purpose of wetting the first surface131before forming the liquid film142. In examples, the nebulizer170may be an ultrasonic nebulizer or the likes.

In some embodiments, the apparatus100further includes a second gas supplier180connected to the holes112. The second gas supplier180may supply suitable gas or air to the first surface131of the semiconductor substrate130through the hole(s)112of the chuck110.

In some embodiments, the apparatus100further includes a rotator190connected to the chuck110. The chuck110may be rotated or revolved when the apparatus100is under operation. The rotation of the chuck110may enhance the cleaning and/or etching effects according to some embodiments of the present disclosure. In examples, the rotator190may be driven by a driving device190a. The driving device190amay programmably control the rotation of the chuck110when the apparatus100is under operation.

FIG. 2Ais a top view schematically illustrating the chuck110according to various embodiments of the present disclosure.

In various embodiments, the principal surface110A of the chuck110has a central region and one or more annular regions surrounding the central region. For example, the principal surface110A has a central region110C and a number of annular regions110S1,110S2,110S3, in which the central region110A has a radius R, and each of the annular regions110S1,110S2and110S3has a width R. In some embodiments, the chuck110and/or the liquid supplying system140are designed to supply a greater liquid amount onto the central region110C than each of the annular regions110S1,110S2and110S3. In yet some embodiments, the liquid amount supplied onto an inner annular region is greater than that supplied onto an outer annular region. For example, the liquid amount supplied onto the annular region110S1is greater than that supplied onto the annular region110S2, and further the liquid amount supplied onto the annular region110S2is greater than that supplied onto the annular region110S3. In some examples, the liquid amount supplied onto the annular region110S1is about 60-80% of that supplied onto the central region110C, the liquid amount supplied onto the annular region110S2is about 30-50% of that supplied onto the central region110C, and the liquid amount supplied onto the annular region110S3is about 18-38% of that supplied onto the central region110C.

In some embodiments, the holes112are arranged in the central region110C and the annular regions110S1,110S2,110S3, as illustrated inFIG. 2A. The total area of the outlets of the holes112in the central region110C is greater than that in each of the annular regions110S1,110S2and110S3. Further, the total area of outlets of the holes112in an inner annular region is greater than that in an outer annular region. For example, the total area of the outlets of the holes112in the annular region110S1is greater than that in the annular region110S2, and further the total area of the outlets of the holes112in the annular region110S2is greater than that in the annular region110S3. In some examples, the total area of the outlets of the holes112in the annular region110S1is about 60-80% of that in the central region110C, the total area of the outlets of the holes in the annular region110S2is about 30-50% of that in the central region110C, and the total area of the outlets of the holes112in the annular region110S3is about 18-38% of that in the central region110C. In yet some examples, the holes112include a central hole112C positioned at the center of chuck110, and the central hole112C has the largest area. In addition, there is no specific limitation on the shapes of the holes112. Illustrated shapes of the outlets of the holes112include circles, triangles, rectangles, rhombuses, crosses and other shapes.

In some embodiments, the holes112may include a number of discharge holes116to drain off the liquid on the principal surface110A. The discharge holes116may be connected to a drainage device such as for example a suction pump.

FIG. 2Bis a cross-sectional view along line BB′ inFIG. 2A. According to yet some embodiments of the present disclosure, the holes112may include a number of swirling holes114for creating a swirl flow145of the liquid film142on the principal surface110A of the chuck110, in a clockwise direction or counterclockwise direction. The swirl flow145of the liquid film142may facilitate the uniformity of etching or cleaning effect on the first surface131of the semiconductor substrate130. Each of the swirling holes114has an axis114A, and each axis114A and the principal surface110A form an included angle θ of less than 90 degrees. In some examples, the included angle θ may range from about 10 degrees to about 80 degrees, specifically about 15 degrees to about 65 degrees, more specifically about 20 degrees to about 60 degrees. In some examples, when the included angle θ is less than a certain value such as for example 10 degrees, some nanometer structures on the first surface131may be damaged. On the other hand, in yet some examples, when the included angle θ is greater than a certain value such as for example 80 degrees, the washing and/or etching effect on the first surface131of the semiconductor substrate130is unsatisfied.

Another aspect of the present disclosure is to provide a method of processing a semiconductor substrate such as for example etching or cleaning the semiconductor substrate.FIG. 3is a flow chart illustrating a method10of processing a semiconductor substrate according to various embodiment of the present disclosure. The method10includes operation12, operation14, operation16, operation18and operation20.FIGS. 4-11collectively illustrate more detailed manufacturing methods as a series of cross-sectional views in accordance with various embodiments of the present disclosure. It will be appreciated that although these methods each illustrate a number of operations, acts and/or features, not all of these operations, acts and/or features are necessarily required, and other un-illustrated operations, acts and/or features may also be present. Also, the ordering of the operations and/or acts in some embodiments can vary from what is illustrated in these figures. In addition, the illustrated operations and/or acts can be further divided into sub-acts in some implementations, while in other implementations some of the illustrated operations and/or acts can be carried out concurrently with one another. It should be noted that the fabrication stages as well as the features in connection withFIGS. 4-11are merely examples. A person skilled in the art will recognize there may be many alternatives, variations and modifications.

In operation12, a semiconductor substrate130is disposed above a chuck110, as illustrated inFIG. 4. The chuck110has a principal surface110A and a plurality of holes112formed thereon. The semiconductor substrate130has a first surface131to be processed and facing the principal surface110A. The semiconductor substrate130further has a second surface132opposite to the first surface131. The semiconductor substrate130is spaced apart from the principal surface110A of the chuck110by a gap134.

In some embodiments, the method10further includes an act of providing a spray172to the first surface131through the holes112after the operation12but prior to the operation14. In some examples, the spray172or droplet is provided for wetting the first surface131of the semiconductor substrate130, and the wetting process may facilitate the following operation14. In some examples, the act of providing the spray172to the first surface131may include applying a nebulizer170such as an ultrasonic nebulizer to generate the spray172.

In operation14, as illustrated inFIG. 5, a flowing liquid layer143is formed on the principal surface110A of the chuck110by supplying liquid141to the principal surface110A through the holes112. In some embodiments, the liquid amount supplied to the central region110C of the chunk is greater than that supplied to the outer annular region110S, and the liquid layer143therefore has a higher surface in the central region110C, as compared to the outer annular region110S. In some examples, the height H1of the liquid layer143in the central region110C is about 10 mm to about 50 mm, specifically about 12 mm to about 30 mm, more specifically about 15 mm to about 25 mm. In some examples, the supplied liquid may include etching chemicals and/or cleaning liquid.

In operation16, as illustrated inFIG. 6-8, the first surface131of the semiconductor substrate130is allowed to be in contact with the liquid layer143such that the liquid layer143flows in the gap134between the first surface131and the principal surface110A of the chuck110. InFIG. 6, the semiconductor substrate130is moved down to softly touch the central portion of the liquid layer143with a high liquid surface in the central region110C. InFIG. 7, the semiconductor substrate130is continuously moved down so that the air149between the liquid surface143S and the first surface131of the semiconductor substrate130may be discharged. In some examples, the acts illustrated inFIGS. 6-7may be repeated several times so to reliably wet the first surface131and drive out the air trapped on the first surface131. Particularly, the semiconductor substrate130may be moved cyclically upwards and downwards in the operation16. InFIG. 8, the semiconductor substrate130is continuously moved down and positioned above the principal surface110A of the chuck110. In this stage, the liquid is continuously supplied from the holes112of the chuck110, and the supplied liquid flows from the holes112through the gap134to the edge of the chuck110, and then leaving the chuck110. In some examples, the gap134is maintained in the range of about 0.1 mm to about 5 mm, specifically about 0.2 mm to about 4 mm, more specifically about 1 mm to about 4 mm in the stage illustrated inFIG. 8. In some examples, the operation16includes removing a material from the first surface131of the semiconductor substrate130.

In operation18, a gas flow152is provided to the second surface132of the semiconductor substrate130. It is noted that the operation18may be started prior to or during the operation16. In some examples, the operation18and the operation16are concurrently carried out. In yet some examples, the operation18is started with the operation14and continues until or after the end of the operation16. In some embodiments, the operation18includes creating a positive pressure space158above the second surface132.

In operation20, the liquid layer143is drained from the edge of the chuck110, as illustrated inFIG. 9. In some embodiments, the act of supplying the liquid141from the holes112is stopped, and then a dry gas182is supplied through the holes112to the gap134between the first surface131and the principal surface110A, and thereby driving the remained liquid layer143out of the gap134. In yet some embodiments, the act of supplying the liquid141from the holes112is stopped, but another liquid is subsequently supplied through the holes112to the principal surface110A. For example, the previously supplied liquid may be a first liquid such as for example etching solution, and the subsequently supplied liquid may be a second liquid such as for example cleaning solution. In yet some embodiments, the method10may include any repeated operation or act described hereinbefore in connection with any ofFIGS. 4-9.

After the operation20, the method may further include other operations or acts. For example, as illustrated inFIG. 10, the first surface131of the semiconductor substrate130is dried when the dry gas182is continuously supplied. Thereafter, the semiconductor substrate130may be moved upwards, as illustrated inFIG. 11.

Advantages of various embodiments of the present disclosure include providing a novel apparatus of processing a semiconductor substrate, and a novel method of processing a semiconductor substrate. The apparatus and method can reliably promise the non-processing surface being free of the working mediums such as for example cleaning liquid and/or etching liquid. Furthermore, the apparatus and method disclosed herein may resolve the issues that the nanometer features such as for example the fin structures of FinFETs are broken or damaged in the cleaning processes and/or wet etching processes. Further, the apparatus and method disclosed herein are suitable for processing large-size substrates.

In accordance with one aspect of some embodiments, an apparatus of processing a semiconductor substrate include a chuck, a holder, a liquid supplying system and a positive pressure unit. The chuck has a principal surface and at least a hole formed thereon. The holder is capable of holding a semiconductor substrate at a position above the principal surface. The liquid supplying system is configured to provide a liquid film onto the principal surface through the hole. The positive pressure unit is configured for providing a gas flow to a space over the chuck.

In accordance with another aspect of some embodiments, an apparatus of processing a semiconductor substrate include a chuck, a holder, a liquid supplying system, a positive pressure unit and a drainage unit. The chuck has a principal surface and a plurality of holes formed thereon. The holder is capable of holding a semiconductor substrate at a position above the principal surface, in which the semiconductor substrate has a first surface to be processed and a second surface opposite to the first surface. The liquid supplying system is disposed to provide a flowing liquid layer onto the principal surface through the holes. When the apparatus is under operation, the first surface of the semiconductor substrate faces the principal surface and in contact with the flowing liquid layer. The positive pressure unit is configured for providing a gas flow to the second surface of the semiconductor substrate. The drainage unit is disposed adjacent to an edge of the chuck for draining liquid from the edge of the chuck.

In accordance with another aspect of some embodiments, a method of processing a semiconductor substrate includes the following operations: (i) disposing a semiconductor substrate over a chuck, in which the chuck has a principal surface and a plurality of holes formed thereon, and the semiconductor substrate has a first surface to be processed and a second surface opposite thereto; (ii) forming a liquid layer flowing on the principal surface of the chuck by supplying liquid to the principal surface through the holes; (iii) allowing the first surface of the semiconductor substrate to be in contact with the liquid layer such that the liquid layer flows between the first surface and the principal surface of the chuck; (iv) providing a gas flow to the second surface of the semiconductor substrate; and (v) draining the liquid layer from an edge of the chuck.