Wet processing apparatuses

A semiconductor apparatus includes a first tank configured to accommodate a first fluid. A second tank is configured to receive overflow of the first fluid into an upper portion of the second tank and to accommodate a second fluid. A cycling system including a first conduit is configured between the first tank and the second tank. The first conduit has an end substantially below a surface of the second fluid. A fluid providing system including a second conduit is fluidly coupled to the second tank and configured to provide the second fluid into the second tank. The second conduit has an end substantially below the surface of the second fluid. An overflow system is coupled to the second tank and configured to remove an upper portion of the second fluid when the surface of the second fluid is substantially equal to or higher than a pre-determined level.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to semiconductor apparatuses, and more particularly to semiconductor wet processing apparatuses.

2. Description of the Related Art

With advances in electronic products, semiconductor technology has been applied widely in manufacturing memories, central processing units (CPUs), liquid crystal displays (LCDs), light emitting diodes (LEDs), laser diodes and other devices or chip sets. In order to achieve high-integration and high-speed requirements, dimensions of semiconductor integrated circuits have been reduced and various materials, such as copper and ultra low-k dielectrics, have been proposed and are being used along with techniques for overcoming manufacturing obstacles associated with these materials and requirements. When scales of integrated circuits are reduced, thickness variations of layers of the integrated circuits may affect electrical performance thereof.

FIG. 1is a cross-sectional view of a traditional nitride removing bench. Referring toFIG. 1, a nitride removing bench100includes an inner tank110next to an outer tank120. The inner tank110accommodates phosphoric acid115for removing silicon nitride from substrates (not shown). The phosphoric acid115overflows into the outer tank120. A cycling system130is configured to cycle phosphoric acid125stored in the outer tank120to the inner tank110through a tube131. The cycling system130also has a pump133, a heater135and a filter137connected in series. A refreshing system140includes a tube141, providing fresh phosphoric acid145at or near to the top surface of the phosphoric acid125. An overflow system150including a tube151is configured to remove the excess of the phosphoric acid125from the outer tank120.

SUMMARY OF THE INVENTION

In accordance with some exemplary embodiments, a semiconductor apparatus includes a first tank configured to accommodate a first fluid. A second tank is configured to receive overflow of the first fluid from the first tank into an upper portion of the second tank and configured to accommodate a second fluid. A cycling system is configured between the first tank and the second tank, the cycling system including at least one first conduit, the at least one first conduit having an end substantially below a surface of the second fluid within the second tank. A fluid providing system is fluidly coupled to the second tank and configured to provide the second fluid into the second tank, the fluid providing system including at least one second conduit, the at least one second conduit having an end substantially below the surface of the second fluid within the second tank. An overflow system is coupled to the second tank and configured to remove an upper portion of the second fluid from the second tank when the surface of the second fluid is substantially equal to or higher than a pre-determined level.

The above and other features will be better understood from the following detailed description of the exemplary embodiments of the invention that is provided in connection with the accompanying drawings.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

This description of the exemplary embodiments is intended to be read in connection with the accompanying drawings, which are to be considered part of the entire written description. In the description, relative terms such as “lower,” “upper,” “horizontal,” “vertical,” “above,” “below,” “up,” “down,” “top” and “bottom” as well as derivatives thereof (e.g., “horizontally,” “downwardly,” “upwardly,” etc.) should be construed to refer to the orientation as then described or as shown in the drawing under discussion. These relative terms are for convenience of description and do not require that the apparatus/device be constructed or operated in a particular orientation.

FIG. 2Ais a cross-sectional view showing an exemplary semiconductor apparatus. Referring toFIG. 2A, a semiconductor apparatus200includes a tank such as an inner tank210. A tank such as an outer tank220may be adjacent to the inner tank210. The inner tank210is configured to accommodate a fluid such as a liquid215containing at least one of acid (e.g., phosphoric acid, perchloric acid, hydroidic acid, hydrobromic acid, hydrochloric acid, sulfuric acid, nitric acid, chloric acid, bromic acid, perbromic acid, iodic acid, periodic acid, fluorantimonic acid, magic acid, carborane sueracid, fluorosulfuric acid, triflic acid or other acid) and/or base (e.g., potassium hydroxide, barium hydroxide, cesium hydroxide, sodium hydroxide, strontium hydroxide, calcium hydroxide, lithium hydroxide, rubidium hydroxide, alanine, ammonia, methylamine, pyridine or other base). The liquid215within the inner tank210is provided to process at least one substrate, such as semiconductor substrates270, immersed therein. The substrates270are disposed on a substrate support213. In some embodiments, the liquid215is provided to remove a material formed on the substrates270and/or clean the substrates270.

In some embodiments, each of the substrates270may include a silicon substrate, a III-V compound substrate, a silicon/germanium (SiGe) substrate, a silicon-on-insulator (SOI) substrate, a display substrate such as a liquid crystal display (LCD), a plasma display, an electro luminescence (EL) lamp display, or a light emitting diode (LED) substrate, for example. In some embodiments, the substrates270may comprise at least one dielectric layer, semiconductor layer, conductive layer, metallic layer, photoresist layer, diode, transistor, device, circuit or other semiconductor structure or various combinations thereof (not shown) are formed therein and/or thereover.

In some embodiments, the liquid215may over flow from the inner tank210into the outer tank220. The outer tank220is configured to accommodate a fluid such as a liquid225. The liquid225may be a mixture of the liquid215flowing from the inner tank210and a liquid245provided from a fluid provider243.

Referring again toFIG. 2A, the semiconductor apparatus200may comprise a cycling system230. The cycling system230may be coupled between the inner tank210and the outer tank220. In some embodiments, the cycling system230may comprise at least one conduit such as conduit231. The cycling system230is configured to deliver the liquid225in the outer tank220to the inner tank210through the conduit231. An end231aof the conduit231may be configured substantially below the surface of the liquid225. In some embodiments, the end231aof the conduit231is distant from an inner bottom surface (not labeled) of the outer tank220between about 3 centimeters (cm) and about 5 cm. Other distances between the end231aof the conduit231and the bottom inner surface (not labeled) of the outer tank220may be used in other embodiments. By the configuration of the conduit231, the liquid225may be desirably delivered from the outer tank220to the inner tank210.

Referring again toFIG. 2A, the cycling system230may comprise at least one pump such as pump233, at least one heater such as heater235and/or at least one filter such as filter237. In some embodiments, the bump233may be coupled to the conduit231. The pump233is operative to transfer the liquid225from the outer tank220to the inner tank210. The pump233may be operative to deliver the liquid225, such that the delivering rate of the liquid225is, for example, between about 19 liters/minute (L/m) and about 20 L/m. In some embodiments, the delivering rate of the liquid225may be about 20 L/m. Other delivery rates of the liquid225provided by the pump233may be used for other embodiments.

In some embodiments, the heater235may be coupled between the pump233and the filter237. The heater235is operative to heat the liquid225flowing therethrough, such that the liquid225having a desired temperature can be delivered into the inner tank210. The heater235may be operative to heat the liquid225to between about 159.5° C. and about 160.5° C. In some embodiments, the heater235may heat the liquid225to a temperature of about 160° C.

In some embodiments, the filter237may be coupled between the inner tank210and the heater235. The filter237is configured to screen particles carried by the liquid225from the outer tank220, such that the liquid225having a desired particle level may be delivered into the inner tank210.

The configurations of the pump233, the heater235and the filter237are not limited to that shown inFIG. 2A. In some embodiments, the pump233may be coupled between the heater235and the filter237. In other embodiments, the filter237may be coupled between the pump233and the heater235. In still other embodiments, at least two of the pump233, the heater235and the filter237are coupled in parallel.

Referring again toFIG. 2A, the semiconductor apparatus200may comprise a fluid providing system240. In some embodiments, the fluid providing system240may be referred to as a refreshing system. The fluid providing system240may be coupled to the outer tank220and configured to provide at least one fluid such as liquid245into the outer tank220. The fluid providing system240may comprise at least one conduit such as conduit241and a fluid provider243. In some embodiments, the fluid provider243may comprise a pump (not shown) configured to deliver the liquid245into the outer tank220. An end241aof the conduit241may be configured substantially below the surface of the liquid225.

In some embodiments, the distance “d1” between the end241aof the conduit241and an inner bottom surface (not labeled) of the outer tank220is between about 3 centimeters (cm) and about 5 cm. Other distances between the end241aof the conduit241and the bottom inner surface (not labeled) of the outer tank220may be used in other embodiments. In some embodiments, the end241aof the conduit241may be near to the end231aof the conduit231. In other embodiments, the end241aof the conduit241and the end231aof the conduit231may substantially equally distant from the top surface (not labeled) of the liquid225. The end241aof the conduit241and the end231aof the conduit231may substantially equally distant from the bottom surface (not labeled) of the outer tank220. In some embodiments, the distance “d1” may be between about 0.1 and about 0.25 times the total depth of the liquid225in outer tank220. By the configuration of the conduit241, the liquid245may be desirably delivered into the outer tank220.

Preferably, there is a sufficiently large distance “d2” between the bottom end241aof the conduit241and the overflow conduit251(described below), so that the overflow chemical exhausted through overflow conduit251is primarily “older” liquid (which may contain impurities), and the liquid remaining in the outer tank220is primarily fresh or recycled liquid from the fluid provider243. One of ordinary skill can readily select a sufficiently large distance d2(based on the flow rate and viscosity of the liquid225) to avoid complete homogenous mixing of the liquid225in outer tank220, and to maintain a desired amount of fresh or recycled liquid in the vicinity of conduit end231a. If the viscosity of liquid225is low and the flow rate through conduit241is relatively high, then a relatively larger distance “d2” may be used to reduce the homogeneity of the liquid in outer tank220, so that the liquid exhausted through overflow conduit251is substantially all “older” liquid. Further, the distance d can readily be selected to reduce turbulence in outer tank220, to further reduce mixing and ensure that the liquid exhausted through overflow conduit251is primarily older liquid.

Referring again toFIG. 2A, the fluid providing system240may include the fluid provider243coupled to the conduit241. The fluid provider243may be operative to deliver the liquid245into the outer tank220at a flow rate between about 0.6 L/m and about 0.9 L/m. In some embodiments, the delivering rate of the liquid245is about 0.7 L/m. Other delivering rates of the liquid245may be used in other exemplary embodiments. The fluid provider243may provide the liquid245, such that a desired amount of the liquid245mixed with the liquid225can be delivered through the conduit231to the inner tank210for processing the substrates270.

Referring again toFIG. 2A, the semiconductor apparatus200may include an overflow system250. The overflow system250is provided to drain the liquid225if the top surface of the liquid225is substantially equal to or higher than a pre-determined level. In some embodiments, the overflow system250may be configured to drain the liquid225if the amount of the liquid225is substantially equal to or higher than a pre-determined amount.

In some embodiments, the overflow system250may include at least one conduit such as conduit251. The conduit251may be configured into a sidewall of the outer tank220, such that if the surface level of the liquid225is higher than the position of the conduit251, the liquid225may flow through the conduit251into a tank (not shown). The use of the overflow system250may control the surface of the liquid225at a desired level over the end231aof the conduit231and/or the end241aof the conduit241.

In some embodiments, the overflow system250may also include a pump (not shown). The pump may be coupled to the conduit251so as to drain the liquid225within the outer tank220if the amount of the liquid225and/or the surface level of the liquid225is substantially equal to or higher than a predetermined value.

AlthoughFIG. 2Ashows an example with an inner tank210configured so that excess liquid spills over into an adjacent outer tank220, other embodiments are contemplated in which an overflow tank or container (not shown) is substituted for the outer tank220, and the overflow tank or container is fluidly coupled to the inner tank210via a conduit (not shown) near the top of the inner tank210. In such a configuration, the overflow tank or container need not be adjacent to the inner tank210.

Following are descriptions of an exemplary process for processing an exemplary substrate.

FIG. 2Bis a cross-sectional view showing an exemplary structure of a substrate. Referring toFIG. 2B, the substrate270may comprise a substrate bulk271. A pad oxide layer273is formed over the substrate bulk271. A pad nitride layer275is formed over the pad oxide layer273. At least one isolation structure such as shallow trench isolation (STI) structures277are formed through the pad oxide layer273and the pad nitride layer275and within the substrate bulk271. In some embodiments, a nitride layer279is formed on the backside of the substrate bulk271while the pad nitride layer275is formed over the pad oxide layer273. After the formation of the STI structures277, the pad nitride layer275and/or the nitride layer279may be subject to a wet processing step in the inner tank210(shown inFIG. 2A).

During the wet processing step, the substrates270are immersed within the liquid215(shown inFIG. 2A). In order to remove the pad nitride layer275and/or the nitride layer279, the liquid215may comprise a phosphorus-containing acid such as a phosphoric acid. Since the liquid215may over flow the sidewall of the inner tank210into the outer tank220, the liquid225may also include a phosphorus-containing acid.

Before processing the substrates270(shown inFIG. 2B), the cycling system230may continuously or periodically deliver the liquid225from the outer tank220to the inner tank210. In some embodiments, the cycling system230may transfer the liquid225at a rate between about 19 L/m and about 20 L/m. When the substrates270are immersed into the liquid215, the pad nitride275and/or the nitride layer279may interact with the phosphoric acid within the liquid215and be gradually removed. After the pad nitride275and/or the nitride layer277are removed, the pad oxide layer273is exposed. Following are exemplary formulas showing the reaction of nitride and phosphoric acid:
Si3N4+4H3PO4+10H2O→Si3O2(OH)8+4NH4H2PO4(1)
SiO2+2H2O→SiO2.(H2O)2(2)

In formula (1), Si3O2(OH)8is unstable and ionizes as SiO2and H2O2. In formula (2), SiO2—(H2O)2is also unstable and ionizes as SiO. SiO ions are active and tend to form oxide. The increase of SiO ions may undesirably thicken the pad oxide layer273due to the attachment of SiO on the surface of the pad oxide layer273. In addition, the interaction of Si3N4and H3PO4reduces the amount of H3PO4within the inner tank215. Accordingly, the fluid provider243provides a desired amount of fresh phosphoric acid into the outer tank225and the cycling system230delivers the liquid225with the mixture of the liquid215and the liquid245into the inner tank210.

FIG. 2Cis a graph showing relationships between numbers of substrate runs and thicknesses of pad oxide layers. Referring toFIG. 2C, curve “a” represents variations of pad oxide thickness by adding fresh phosphoric acid on or near to the surface of the liquid125of the outer tank120at 2 liters per run as shown inFIG. 1; curve “b” represents variations of pad oxide thickness by adding fresh phosphoric acid on or near to the surface of the liquid125of the outer tank120at 5 liters per run as shown inFIG. 1; and curve “c” represents variations of pad oxide thickness by the method and apparatus described in conjunction withFIG. 2A.

Referring again toFIG. 2C, the pad oxide thickness indicated by curves “a” and “b” rapidly increases with the number of wafers, regardless of whether the amount of fresh phosphoric acid added is 2 liters or 5 liters. The curve “c” shows that the pad oxide thickness smoothly increases even if many runs of substrates270have been processed in the inner tank210according to the apparatuses and methods described in conjunction withFIG. 2A. Therefore, the thickness of the pad oxide layer273may be desirably controlled. In some embodiments, the thickness variation of the pad oxide layer273may be improved from about 40 Å to about 5 Å. By using the apparatuses described in conjunction withFIG. 2A, the substrates270processed at different runs may have desirably controlled thickness variations of the pad oxide layers273and/or may have pad oxide layers273with substantially the same thickness. Accordingly, when the substrates270processed in different runs are subject to a subsequent process, such as an ion implantation process, implantation profiles of the substrates270may be desirably controlled and achieved.

FIG. 2Dis a cross-sectional view showing another exemplary semiconductor apparatus. InFIG. 2D, like items are indicated by reference numerals having the same value as inFIG. 2A. In some embodiments, the semiconductor apparatus201may include at least one storage medium such as storage medium265. The storage medium265is configured to store the information regarding the number of the substrates270to be processed within the inner tank210. The storage medium265may comprise, for example, at least one of a random access memory (RAM), floppy diskettes, read only memories (ROMs), flash drive, CD-ROMs, DVD-ROMs, hard drives, high density (e.g., “ZIP™”) removable disks or any other computer-readable storage medium.

In some embodiments, the semiconductor apparatus210may comprise at least one processor such as processor260. The processor260may be coupled to the storage medium265and the fluid providing system240, e.g., the fluid provider243. The processor260may be configured to generate a signal261corresponding to the number of the substrates270so as to control the flow rate and/or amount of the liquid245provided into the outer tank220. In some embodiments, the processor260may calculate a desired amount of the liquid245to be provided into the outer tank220according to formula (3) shown below:
Y=50−3250/(65+0.28X)  (3)

Y represents the amount (L) of the liquid245to be added and X represents a number of the substrates270to be processed in the inner tank210.

In still other embodiments, the present invention may be embodied in the form of computer-implemented processes and apparatus for practicing those processes. The present invention may also be embodied in the form of computer program code embodied in tangible media, such as floppy diskettes, read only memories (ROMs), CD-ROMs, hard drives, “ZIP™” high density disk drives, flash memory drives, or any other computer-readable storage medium, wherein, when the computer program code is loaded into and executed by a computer, the computer becomes an apparatus for practicing the invention. The present invention may also be embodied in the form of computer program code, for example, whether stored in a storage medium, loaded into and/or executed by a computer, or transmitted over a suitable transmission medium, such as over the electrical wiring or cabling, through fiber optics, or via electromagnetic radiation, wherein, when the computer program code is loaded into and executed by a computer, the computer becomes an apparatus for practicing the invention. When implemented on a general-purpose processor, the computer program code segments configure the processor to create specific logic circuits.

Although the present invention has been described in terms of exemplary embodiments, it is not limited thereto. Rather, the appended claims should be construed broadly to include other variants and embodiments of the invention which may be made by those skilled in the field of this art without departing from the scope and range of equivalents of the invention.