WET BENCH PROCESS WITH IN-SITU PRE-TREATMENT OPERATION

Embodiments of the present disclosure relates to a wet bench processing including an in-situ pre-treatment prior to performing the first set of wet bench operations. The pre-treatment may include a pre-clean operation and/or a pre-heat operation. The pre-treatment may be performed in one of the existing ONB tanks without requiring adding new tanks to an existing wet bench tool. The pre-clean operation removes particles from a batch of wafers to avoid or reduce cross-contamination and defect issues, thus improving the yield rate of the wet bench process. The pre-heat operation provides better control and stabilize the temperature in the CHB tank to stabilize the process, such as to stabilize an etch rate.

BACKGROUND

During semiconductor processing, etching is used to selectively remove one or more material from a silicon substrate or from thin films on the substrate surface. Etching may be performed through two methods. One method is dry etching using gaseous etchant, while another method is wet etching using liquid etchant solutions. Examples of dry etching may include plasma etching, ion beam etching and reactive ion etching. Examples of wet etching may include immersion etching and spray etching.

A common device for wet chemical etching of semiconductor wafers is an immersion chemical etching device, also called a wet bench tool, which includes a plurality of chemical tanks, cleaning tanks, robots, and driers. Batches of wafers are moved in sequence through the tanks, typically by operation of a computer-controlled automated apparatus.

Because a batch of wafers are processed simultaneously in a tank during wet bench process, cross contamination may occur causing defects. Therefore, there is a need to reduce cross contaminations and improve yield rate during wet bench process.

DETAILED DESCRIPTION

FIG.1Ais a schematic block diagram of a wet bench tool100in accordance with some embodiments of the present disclosure. The wet bench tool100may include one or more ONB (once through bath) tanks102and one or more CHB (concentrated heated bath) tanks104. In some embodiments, the ONB tanks102and the CHB tanks104may be arranged in pairs and each pair as a tank set103. As shown inFIG.1A, three tank sets103A,103B,103C are shown. The tank set103A includes the ONB tank102A and the CHB tank104A. The tank set103B includes the ONB tank102B and the CHB tank104B. The tank set103C includes the ONB tank102C and the CHB tank104C. Any numbers of tank sets may be included in the wet bench tool100as desired for various applications and operations. The CHB tank104in each tank set may be configured to retain a process solution. During operation, a batch of wafers101are immersed in the process solution. The process solution used to achieve a target wet process, such as wet etching. The process solution in the CHB tank104may be circulated and used by many batches of wafers101. The ONB tank102in each tank set103A,103B,103C is configured to retain a diluted process solution, a rinse solution, and/or deionized water. One or more chemical source114may be connected to the ONB tank102to selectively provide one or more processing solutions to the ONB tank102. After being processed in the CHB tank104, a batch of wafers101are then dipped into the ONB tank102in the corresponding to be rinsed off and/or cleaned. The ONB tank102provides a fresh solution for each batch of wafers101.

In some embodiments, the wet bench tool100may also include a dryer106. The dryer106may be configured to dry the wafers after processing in the CHB tanks104and the ONB tanks102by spinning or using isopropyl alcohol (IPA). In some embodiments, the dryer106is a low pressure dryer, such as a dryer operates by the Marangoni drying effect using IPA (isopropyl alcohol).

The wet bench tool100may include a loading station112and a wafer transfer robot109. At the loading station112, wafers to be processed may be loaded from cassettes to one or more batch wafer carriers110using the wafer transfer robot109. A batch of wafers101may enter the wet bench tool100in a batch wafer carrier110, which may slide along a lifter slide108positioned over the ONB tanks102, the CHB tanks104, and the dryer106. The batch wafer carriers110may slide along the lifter slide108to move batches of wafers101among the ONB tanks102, the CHB tanks104, and the dryer106. The batch wafer carriers110may be lowered into any one of the ONB tanks102, the CHB tanks104, and the dryer106to process the wafers in batches therein. After processing, the batch wafer carriers110may be lifted from the corresponding one of the ONB tanks102, the CHB tanks104, and the dryer106and moved to the subsequent location. When process is complete, the wafer transfer robot109may unload the batch of wafers from the batch wafer carriers110to cassettes.

FIG.1Bis a schematic view of a batch of wafers disposed in the batch wafer carrier110according to some embodiments. As shown inFIG.1B, the batch wafer carrier110may include a frame118to support a batch of wafers in a parallel manner with gaps between neighboring wafers such that surfaces of each wafer in the batch wafer carrier110. The batch wafer carrier110may include an actuator116configured to slide along the lifter slide108and/or move vertically in and out tank set103.

FIG.1Cis a schematic view of the ONB tank102in the wet bench tool100according to embodiments of the present disclosure. The ONB tank102includes a housing120defining a processing chamber122therein. The housing120may have an upper opening to allow passage of wafers being processed. The ONB tank102may include a chemical manifold121configured to selective supply one or more processing chemicals to the processing chamber122. The chemical manifold121may be connected to chemical source114and a deionized water source124to generate processing solutions including various chemicals at various concentration. In some embodiments, the processing chamber122may be directly connected to the deionized water source124. Processing solutions and deionized water may be supplied to the processing chamber122continuously through spraying jets or any suitable inlets. The processing chamber122is also connected to a drain123so that the processing solution may be drained after each batch of wafers are processed. In some embodiments, the ONB tank102further includes a heater125. In some embodiments, the heater125may be connected to the deionized water source124to supply a flow of heated deionized water to the processing chamber122, as shown inFIG.1C. In other embodiments, the heater125may be disposed between the manifold121and the processing chamber122to heat any solution supplied to the ONB tank102, as shown inFIG.1A. A batch of wafers disposed in the ONB tank102, for example positioned on a batch wafer carrier, may be rinsed by processing solution or deionized water sprayed from one or more jets, or immersed in a processing solution in the processing chamber122.

In some embodiments, the heater125and the manifold121may be retrofitted to an existing wet bench tool. In some embodiments, the heater125and manifold121may be included in every ONB tank102in the wet bench tool100so that a pre-treatment according to present disclosure may be performed with maximum flexibility. In other embodiments, the heater125and the manifold121may be included in selected ONB tank102to reduce cost of the tool and operation. In some embodiments, both the heater125and the manifold121are included in the ONB tank102so that the ONB tank102may perform various pre-treatment according to the present disclosure. In other embodiments, only one of the heater125and the manifold121is included in the ONB tank102to allow the ONB tank102to one of the pre-clean or pre-heat operation according to the present disclosure.

FIG.1Dis a schematic view of the CHB tank104in the wet bench tool100according to the present disclosure. The CHB tank104includes a housing140defining a processing chamber142. The CHB tank104is configured to retain a processing solution within the processing chamber142, in which a batch of wafers may be immersed for a desired processing, such as etching, and cleaning. The CHB tank104may include a pump143positioned in a circulate conduit146to circulate the processing solution in the processing chamber142. The CHB tank104may include a filter144positioned to heat the processing solution flowing through the circulate conduit146. A heater145may be disposed in the circulate conduit146to remove impurities from the processing solution.

FIG.2is a flow chart of a method200for processing a batch of wafers with one or more liquid chemical solutions according to embodiments of the present disclosure. The method200may be used to perform a wet bench process, such as a wet etching process, a wet cleaning process, or the like. The method200may be performed using a wet bench tool, such as the wet bench tool100, described above.FIGS.3A-3Gare partial view of a wet bench tool during various stages of processing a batch of wafers according to the method200.

A wet bench process usually includes one or more sets of wet bench operations, which are sequentially performed. Each set of wet bench operation is in a tank set, such as the tank sets103A/103B/103C described above. Each set of wet bench operations includes two steps using a tank set. In the first operation, a batch of wafers to be processed are first immersed into a heated, high concentration processing solution, such as an acid bath, in the CHB tank of a tank set. In the second operation, the batch of wafers are rinsed with a diluted processing solution at a lower temperature in the ONB tank of the tank set.

Because the processing solution in CHB tanks moves as a circulating flow in a non-draining mode tank, wafers processed in CHB tanks are susceptible to cross-contamination. For example, organic or particulate contaminations accumulate on front side, back side or bevel of the wafers may be dislodged during immersion and travel to other wafers in the same batch or other wafers in the subsequent batches, resulting in cross-contamination causing defects on the processed wafers. The cross-contamination becomes more severe as batch size increases.

In method200, an in-situ pre-treatment is performed prior to performing the first set of wet bench operations. In other words, when a batch of wafers enter the wet bench tool to be processed with one or more sets of two-step wet bench operations, instead of immersing the batch of wafers in the first CHB tank, an in-situ pre-treatment is first performed in one of the ONB tanks prior to being transferred to and processed in the first CHB tank. The pre-treatment may include one or more operations, such as a pre-cleaning operation, a pre-heating operation. In some embodiments, the pre-treatment may be performed in one of the existing ONB tanks without requiring adding new tanks to an existing wet bench tool. The pre-treatment removes particles from a batch of wafers to avoid or reduce cross-contamination and defect issues, thus improving the yield rate of the wet bench process. The pre-treatment also may also provide better control and stabilize the temperature in the CHB tank to stabilize the process, such as to stabilize an etch rate.

In operation210, a batch of wafers101are loaded to a wet bench tool, such as the wet bench tool100. As shown inFIG.3A, a batch of wafers101are loaded into a batch wafer carrier110. The batch wafer carrier110may move along the lifter slide108towards the tank set103A. At this stage, the batch of wafers101are at room temperature.

In operation220, the batch of wafers101are pre-treated after entering the wet bench tool100. The pre-treatment is performed prior to any wet bench processes. The pre-treatment is an in-site treatment as it is performed within the wet bench tool100and immediately before a wet bend process. The pre-treatment may be performed in one of the ONB tank102in the wet bench tool100. In some embodiments, the pre-treatment is performed in an ONB tank102of the tank set103where the first wet-bench operation is to be performed. As shown inFIG.3B, the pre-treatment is performed in the ONB tank102A of the tank set103A. The CHB tank104A of the tank set103A is prepared to perform the first wet bench process. However, the pre-treatment may be performed in any ONB tank102A,102B,102C in the wet bench tool100that is idle from the wet bench operation set. As shown inFIG.3A, the batch of wafers101are lowered in the ONB tank102A wherein the pre-treatment is performed, while the CHB tank104A retains a processing solution304configured to perform the first operation of a wet bench operation set.

In some embodiments, the in-situ pre-treatment may be performed in a designated ONB tank102for every batch of incoming wafers. In other embodiments, the in-situ pre-treatment may be performed different ONB tanks for different batches of incoming wafers. For example, the in-situ pre-treatment may be performed in an ONB tank having suitable length of idle time from regular wet-bench processing at the time.

The pre-treatment may include any suitable operations to remove organic contaminations and/or particles from the wafers, or to heat the wafers, or a combination thereof. Depending on the structure and/or materials on the wafers to be processed, the pre-treatment may include a pre-clean process, a pre-heat process, or a combination of pre-clean and pre-heat.

In some embodiments, the pre-treatment in operation220includes an in-situ pre-clean operation. An in-situ pre-clean operation may be performed during pre-treatment in operation220when the accuracy of the etching rate is not high, for example, when structure on the wafers has an etch stop layer. The in-situ pre-clean operation removes organic contamination and/or particles to avoid or reduce cross contamination in the subsequent CHB tank.

The in-situ pre-cleaning operation may be performed by washing or rinsing the wafers with a cleaning solution at about room temperature. In some embodiments, the cleaning solution may be a low concentration IPA, SC1 (standard cleaning solution), or other chemicals to remove organic contamination or particle type defect source from the wafers. In some embodiments, the cleaning solution may include the same chemical as the processing solution used for the subsequent wet bench process at a lower concentration. For example, the cleaning solution may be a diluted solution of a processing solution306(discussed in operation230). In other embodiments, the cleaning solution includes different chemicals from the processing solution used in subsequent wet bench process.

In some embodiments, the cleaning solution may be IPA. In some embodiments, the cleaning solution may be 100% IPA. A cleaning solution of IPA may eliminate or reduce organic contamination. In other embodiments, the cleaning solution may be SC1, such as a solution including 50 parts of deionized water, 1 part of Ammonium hydroxide (NH4OH), and 2 part of hydrogen peroxide (H2O2). SC1 is used to remove particles from substrates and as a surface preparation before going into growth furnaces. Due to the pH of the solution, particles removed from the surface are more likely to stay in solution than re-deposit back on the wafer surface. The SC1 solution may eliminate or reduce particle contamination. Other chemical solution may be used according to process. The pre-clean operation may about room temperature, such as in a temperature range between about 15° C. and about 30° C.

In some embodiments, the pre-cleaning operation includes one or more rinsing cycles. Each rinsing cycle includes a rinsing operation and quick dipping operation performed in an ONB tank. In some embodiments, each pre-clean cycle may be performed for about 11 minutes to about 15 minutes. A cycle time shorter than 11 minutes may not be long enough to efficiently rinse all areas of the wafers, and a cycle time longer than 15 minutes may cause schedule issues or increase cost without providing additional benefit.

FIG.4schematically illustrates a rinsing cycle in the pre-clean operation according to the present disclosure. A cleaning solution302, such as a low concentration IPA or SC1 solution discussed above, is sprayed over the batch of wafers101to rinse the batch of wafers101. The batch of wafers101may be spinning in the ONB tank102during rinsing. After rinsing, the batch of wafers101are dipped into the cleaning solution302briefly to conclude a rinsing cycle. In some embodiments, after dipping, the batch of wafers101are transferred towards the adjacent CHB tank where the first wet bench operation set is to be performed, as described in operation230.

In some embodiments, the rinsing cycle may be repeated prior to the operation230. The rinsing cycle may be repeated in the same ONB tank or a different ONB tank according to scheduling of the wet bench tool100. In some embodiments, two or more rinsing cycles may be performed using two or more different cleaning solutions. For example, a first rinsing cycle may be performed using a cleaning solution including IAP, and a second rinsing cycle may be performed using a cleaning solution including SC1.

In some embodiments, the pre-treatment in operation220includes an in-situ pre-heat operation. For example, an in-situ pre-heat operation is performed during pre-treatment in operation220when the accuracy of the etching rate is high or when the structures on the wafers may be damaged by chemicals in a cleaning solution, such as the cleaning solution used in the in-situ pre-clean operation described above. For example, when structures on the wafers do not have an etch stop layer, such as structures include exposed SiGe layers in a selective etching process. The in-site pre-heat operation reduces the temperature drop occurs during in subsequent process in the CHB tank shortening the temperature stabilization time, thus improving process uniformity.

The in-situ pre-heat operation may be performed by washing or rinsing the wafers with a high temperature deionized water to pre-heat the wafers for a period of time. In some embodiments, the wafers may be rinsed in a flow of high temperature deionized water about 5 minutes to about 9 minutes. A time period shorter than 5 minutes may not be long enough to uniformly heat all areas of the wafers, and a time period longer than 9 minutes may cause schedule issues, heat the wafers at a temperature higher than desired, or not further heat the wafers beyond the temperature of the deionized water. In some embodiments, the in-situ pre-heat operation may heat wafers to a temperature in a range between 65° C. and 95° C. A temperature lower than 65° C. may not provide enough stabilizing benefit. A temperature higher than 95° C. may not be uniformly achieved as the temperature is close to boiling point of the water. In some embodiments, the in-situ pre-heat operation may raise the wafer temperature in a range between about 45° C. and about 70° C. In some embodiments, the in-situ pre-heat operation may heat wafers to reduce a temperature gap between the wafer temperature and the solution temperature in the subsequent CHB tank by about 30% to about 60%. For example, the temperature gap between the wafers and the solution in the subsequent CHB tank is about 140° C. (e.g. the process solution in the subsequent CBH tank is about 160° C. and the wafer temperature is about 20° C.), the in-situ pre-heat may reduce the temperature gap to arrange between 98° C. and 56° C. (e.g. by heating the wafers to a temperature to in arrange between 62° C. and 94° C.).

FIG.5schematically illustrates a pre-heat operation according to the present disclosure. A flow of heated deionized water310is sprayed over the batch of wafers101to rinse the batch of wafers101. The batch of wafers101may be spinning in the ONB tank102during rinsing. After rinsing, the batch of wafers101are immediately transferred to the CHB tank configured for the subsequent processing, or the first wet-bench process, to be described in operation230.

In some embodiments, the pre-treatment in operation220includes a combination of an in-situ pre-clean operation and an in-situ pre-heat operation. The combined operation may be performed during pre-treatment in operation220when the structures on the wafers do not have vulnerable material or structures are not easily damaged by a pre-clean and pre-heat operations, and the accuracy of etching rate is not high. In the combined operation, the pre-clean and pre-heat operations are similar to the individually performed operations described above. The combined in-situ pre-clean and pre-heat operation removes organic contamination and/or particles to avoid or reduce cross contamination in the subsequent CHB tank, and also reduces the temperature drop occurs during in subsequent process in the CHB tank shortening the temperature stabilization time, thus improving process uniformity.

In some embodiments, the combined pre-clean and pre-heat operation may be performed in the same ONB tank. In other embodiments, the pre-clean operation may be performed in different ONB tanks.FIG.6schematically illustrates a combined pre-clean and pre-heat operation according to the present disclosure.

In some embodiments, the pre-cleaning operation includes one or more rinsing cycles. Each rinsing cycle includes a rinsing operation and quick dipping operation performed in an ONB tank. In some embodiments, each pre-clean cycle may be performed for about 11 minutes to about 15 minutes. A cleaning solution302, such as a low concentration IPA or SC1 solution discussed above, is sprayed over the batch of wafers101to rinse the batch of wafers101. The batch of wafers101may be spinning in the ONB tank102during rinsing. After rinsing, the batch of wafers101are dipped into the cleaning solution302briefly to conclude a rinsing cycle. In some embodiments, additional rinsing cycle may be performed using the same or different cleaning solutions.

After rinsing cycles are completed, the cleaning solution302is drained from the ONB than102to conclude the in-situ pre-clean operation. A pre-heat operation is then performed. A flow of heated deionized water310is then sprayed over the batch of wafers101to rinse and pre-heat the batch of wafers101. The batch of wafers101may be spinning in the ONB tank102during rinsing. The in-situ pre-heat operation may be performed by washing or rinsing the wafers with a high temperature deionized water to pre-heat the wafers for a period of time. In some embodiments, the wafers may be rinsed in a flow of high temperature deionized water about 5 minutes to about 9 minutes. In some embodiments, the in-situ pre-heat operation may heat wafers to a temperature in a range between 65° C. and 95° C.

After rinsing, the batch of wafers101are immediately transferred to the CHB tank configured for the subsequent processing, or the first wet-bench process, to be described in operation230.

In operations230and240, a set of wet bench operation is performed. The set of wet bench operations may be performed in one tank set103, where operation230is performed in the CHB tank104and operation240is performed in the ONB tank102of the tank set103. The operation230is a high-temperature high-concentration process performed in a recirculated solution while the operation240is a low-temperature low-concentration rinse and wash process performed in a fresh flow of processing solution. Depending on the particular processing, one or more sets of wet bench operations may be sequentially performed in the wet bench tool100. For example, one or more sets of wet bench operations are performed sequentially in different tank sets103. The operations230and240may be a conventional aspect of conventional wet cleaning tools and thus be discussed herein in brevity and as examples.

As shown inFIG.3C, after the in-situ pre-treatment in operation220, the batch of wafers101are immediately lifted from the ONB tank102and transferred to the CHB tank104to be performed the first operation230to obtain the maximum benefit of the in-site pre-treatment. The ONB tank102is then drained for a subsequent operation, which may be the operation240or an operation220for a batch of wafers newly entered into the wet bench tool100.

In operation230, as shown inFIG.3D, the batch of pre-treated wafers101are lowered into the CHB tank104and immersed into a process solution304. The processing solution304may be various chemicals to achieve various wet bench applications. For example, the processing solution304may be phosphoric acid (H3PO4), buffered hydrofluoric acid (BHF), peroxymonosulfuric acid (H2SO5, or Caro), a high concentration hydrofluoric acid (HF), a high concentration SC1 (such as SC1 including 5 parts of deionized water, 1 part of NH4OH, and 1 part of H2O2), a high concentration SC2 (such as SC1 solution including 6 parts deionized water, 1 part of HCl, and 1 part of H2O2), or other suitable wet processing agents.

In some embodiments, the processing solution304is hot phosphoric acid, H3PO4, may be maintained at a temperature in a range of between about 70° C. and about 160° C. Particularly, the processing solution304may be maintained at a temperature in a range of between about 140° C. and about 160° C. The processing solution304may be used to selectively etch a material layer, such as a silicon nitride containing layer, with the following reactions:

In some embodiments, a circulation process is performed via a circulate conduit (such as the circulate conduit146inFIG.1D). During the circulation process, the processing solution304are drawn from the CHB tank104via the circulate conduit and back into the CHB tank104. In some embodiments, after the circulation process, a substantially homogenous liquid processing solution304is provided in the CHB tank104. In some embodiments, in the circulation process, particles in the processing solution304are filtered by a filter, such as the filter144inFIG.1D, of the circulate conduit. In some embodiments, in the circulation process, the processing solution304is heated to a desired temperature for processing by a heater, such as the heater145inFIG.1D, in the circulate conduit. In some embodiments, the circulation process is continuously operated except that a maintenance process is performed.

In operation230, the wafers101are immersed in the processing solution304for a period of time to achieve desired processing results, and then lifted from the CHB tank104and transferred towards the ONB tank102wherein the second operation of the wet bench operation set is to be performed, as shown inFIG.3E.

In operation240, as shown inFIG.3F, the wafers101are lowered into ONB tank102for the second operation of the wet bench process. In some embodiments, the wafers101may be immersed within a processing solution306in the ONB tank102for a quick dump rinse (QDR) or a quick etch rinse (QER) process. The processing solution306may be a deionized water, or a dilute solution, such as a low concentration SC1, a low concentration SC2, a diluted HF, or other suitable wet processing agents. After operation240, the wafers are lifted from the ONB tank102and the processing solution306is drained, as shown inFIG.3G.

The operations230,240may be repeated in other tank sets103according to the application. When all wet bench operation sets are completed, the wafers101may be dried at operation250.

At operation250, the wafers101may be dried at a drying chamber, such as the dryer106. In some embodiments, the wafers101may be dried by a conventional drying process.

At operation260, the dried wafers101may be unloaded from the batch wafer carrier110to a cassette and exit the wet bench tool100.

Even though methods according to the present disclosure are described with a wet bench tool with vertical tanks, embodiments of the present disclosure may be performed in any wet processing tools for an in-situ pre-treatment to remove organic contamination, remove particles, or pre-heat, or any other suitable treatment that is beneficial to the subsequent wet etch, wet clean, or similar processes. Even though methods of the present disclosure may improve yield in batch processing, the in-situ pre-treatment according to the present disclosure may be used prior to single wafer wet processing.

The pre-clean operation included in the in-situ pre-treatment according to the present disclosure has reduced cross contamination in batch wet processing, thus increasing yield by reducing defects, and increasing productivity by allowing the wafers to be processed in larger batches.

The pre-heat operation included in the in-situ pre-treatment according to the present disclosure has reduced temperature stabilizing time, thus improve etch selectivity. When the wafer temperatures are lower significantly lower than the processing solution, the temperature in the processing solution drops upon immersion of the wafers, which is sometimes referred to as Bench Effect. The larger the batch size, the more significant the temperature drop. Temperature drop in the processing solution not only affects etch rate but also affects etch selectivity.

FIG.7is a schematic graph of temperature-time curve in a CHB tank for a wet bench process. In the graph shownFIG.7, the x-axis indicates time after a batch of wafers are immersed into a processing solution comprising hot phosphoric acid maintained at a temperature at T0 prior to the wafers are immersed. The y-axis indicates the temperature of the process solution after the wafers are immersed. Curve702is the temperature-time curve in a process when the wafers are not pre-heated. Curve702is a temperature-time curve in a process when the wafers are pre-heated according to operation220of the present disclosure. In curve702, the temperature of the processing solution dipped amount of dT1. In curve704, temperature of the processing solution dipped amount of dT2. dT2 is about 50% of dT1. In curve702, the temperature of the processing solution returned to T0 at time t1. In curve704, the temperature of the processing solution returned to T0 at time t2. Time t2is about 33% shorter than time t1. Thus, the in-situ pre-heat operation has reduced the temperature drop in the CHB by about 50% and shortened the temperature stabilization period by about 33%.

Various embodiments or examples described herein offer multiple advantages over the state-of-art technology. The in-situ pre-treatment according to present disclosure removes or reduces organic contamination and particles from a batch of wafers to avoid or reduce cross-contamination and defect issues, thus improving the yield rate of the wet bench process. The pre-treatment also may also provide better control and stabilize the temperature in the CHB tank to stabilize the process, such as to stabilize an etch rate. The in-site pre-treatment may be performed in one of the existing ONB tanks without adding processing changes to an existing wet bench tool.

Some embodiments of the present provide a method comprising loading a batch of wafers into a wet bench tool comprising a CHB (concentrated heated bath) tank and a first ONB (once through bath) tank, wherein the batch of wafers are at a first temperature, upon loading the batch of wafers, pre-treating the batch of wafers in the first ONB tank with a pre-treatment solution; immersing the batch of wafers in a process solution stored in the CHB tank after pre-treating the batch of wafers in the first ONB tank, wherein the process solution is at a second temperature, and the second temperature is higher than the first temperature; and rinsing the batch of wafers in a rinse solution.

Some embodiments of the present disclosure provide a method comprising pre-heating a batch of wafers from a first temperature to a second temperature in a ONB tank of a wet bench tool, wherein the second temperature is a range between about 65° C. and about 95° C.; upon completion of pre-heating, moving the batch of wafers from the ONB tank to a CHB tank in the wet bench tool to immerse the batch of wafers in a processing solution in the CHB tank, wherein the processing solution is at a third temperature prior to immersing the batch of wafers, and the third temperature is higher than the second temperature; and moving the batch of wafers from the CHB tank to the ONB tank to rinse the batch of wafers in the ONB tank with a rinsing solution.

Some embodiments of the present disclosure provide a method, comprising loading a batch of wafers into a wet bench tool comprising a tank set, wherein the tank set comprises: a CHB tank having a processing solution, wherein the processing solution being recirculated; and a ONB tank in connection with one or more chemical supply bath and a heater; upon loading the batch of wafers, pre-treating the batch of wafers in the ONB tank with a pre-cleaning solution supplied from the one or more chemical supply bath or a heated deionized water; after pre-treating the batch of wafers, performing a wet bench operation set comprising: immersing the batch of wafers in the processing solution in the CHB tank; and rinsing the batch of wafers in the ONB tank.