WO2012165861A2

WO2012165861A2 - Substrate processing system and substrate processing method using the same

Info

Publication number: WO2012165861A2
Application number: PCT/KR2012/004268
Authority: WO
Inventors: Jin-Ok Jung; Sang-Sun Lee; Jung-Min Han
Original assignee: Tes Co., Ltd
Priority date: 2011-05-31
Filing date: 2012-05-30
Publication date: 2012-12-06
Also published as: TWI503877B; TWI538035B; TW201248705A; KR101290527B1; KR20120133341A; WO2012165861A3; TW201523714A

Abstract

Provided are a substrate processing system with an improved structure which can prevent a damage from occurring in a lower layer and efficiently remove both etching byproducts and fumes, and a substrate processing method using the same. The substrate processing system includes a wet cleaning module configured to supply a cleaning solutionto a substrate to clean a surface of the substrate and dry the cleaned substrate, and a dry cleaning module configured to spray a cleaning gas containing HF gas to the substrate to etch a silicon oxide layer formed on the substrate.

Description

SUBSTRATE PROCESSING SYSTEM AND SUBSTRATE PROCESSING METHOD USING THE SAME

The present invention relates to a substrate processing system and a substrate processing method using the same, and more particularly, to a substrate processing system and a substrate processing method using the same that remove impurities, a silicon oxide layer, and fumes from a substrate after a process of etching the substrate.

As the degree of integration of semiconductor devices becomes higher, the importance of isolation technology for electrically isolating adjacent devices increases. A shallow trench isolation (STI) forming method, which is a type of isolation technique used in semiconductor processing, forms a trench that limits an active area in a semiconductor substrate, and forms an isolation layer by burying the inside of the trench with an insulating material.

FIG. 1 is a sectional view for describing a typical isolation layer forming method.

Referring to FIG. 1, a pad oxide layer and a nitride layer are sequentially formed on a semiconductor substrate 10. A photoresist pattern (not shown) is formed on the nitride layer, and then a nitride pattern 30 is formed by patterning the nitride layer with the photoresist pattern. A pad oxide pattern 20 and a trench 40 that limits an active area of the semiconductor substrate 10 are formed by etching the pad oxide layer and the semiconductor substrate 10 with the nitride pattern 30 as an etching mask.

In a subsequent process, the photoresist pattern is removed by ashing, an etching byproduct and the like are removed by wet cleaning, an insulating material is buried inside the trench 40, and then the nitride pattern 30 and the pad oxide pattern 20 are removed, thereby completing an isolation layer.

However, when a lower layer is formed as a PSG layer, a BPSG layer, an SOD layer, or a relatively soft oxide layer, damage occurs in the lower layer (i.e., the lower layer is excessively etched.) due to a cleaning solution in wet cleaning.

To overcomethese limitations, instead of wet cleaning, dry cleaning with HF gas is recently attracting much attention as an alternative process. However, in applying dry cleaning, a time delay occurs between processes due to the transfer of a substrate between an etching device for forming a pattern and a dry cleaning device used after etching, and thus, impurities called fumes are generated inside a pattern.

FIG. 2 is a top view schematically illustrating a state in which the trench 40 is formed in the semiconductor substrate 10 by an etching device, the semiconductor substrate 10 is exposed to the atmosphere when being transferred to a dry cleaning device, and thus fumes 50 are generated inside the trench 40.

As illustrated, the fumes 50 are generated on the semiconductor substrate 10, and analysis with XPS/AES shows that they contain SiO₂. This can be understood as a state in which halogen ingredients, such as F, Cl, and Br, in etching gas used in an etching process are left inside thetrench 40 and then react with moisture in the atmosphere when exposed to the atmosphere to form solid hydrates. Such fumes become a problem in an STI process and anyprocess to which dry cleaning is applied after patterning, for example, a process of forming gate lines and bit lines.

That is, by cleaning an etching byproduct through wet cleaning as a subsequent process after etching, fumes arenot formed by hydrolysis with H₂O₂ or buffered oxide etchant (BOE) used in wet cleaning. However, as described above, due to damage that occurs in the lower layer, it is impossible to apply wet cleaning. On the contrary, fumes result from dry cleaning.

Therefore, the development of a new substrate processing system is required for preventing damage from occurring in the lower layer and moreover removing both an etching byproduct and fumes.

Embodiments of the present invention provide a substrate processing system with an improved structure that can prevent damage from occurring in a lower layer and efficiently remove both an etching byproduct and fumes, and a substrate processing method using the same.

In one aspect, a substrate processing system includes: a wet cleaning module configured to supply a cleaning solution to a substrate to clean a surface of the substrate, and dry the cleaned substrate; and a dry cleaning module configured to spray a cleaning gas onto the substrate to etch a silicon oxide layer formed on the substrate, the cleaning gas containing HF gas.

According to an embodiment of the present invention, the substrate processing system may further include: a cassette module configured to receive a substrate before or after processing the substrate an atmospheric transfer module configured to transfer the substrate received in the cassette module; a vacuum transfer module connected to the dry cleaning module and configured to transfer the substrate to the dry cleaning module in a vacuum state; and a loadlock module connected to the vacuum transfer module and changing a pressure between an atmospheric state and the vacuum state.

In another aspect, a substrate processing method includes: performing a dry cleaning process of spraying a cleaning gas onto a substrate to remove a silicon oxide layer formed on the substrate, the cleaning gas containingHF gas; and performing a wet cleaning process of supplying the cleaning solution to the substrate to clean a surface of the substrate, and drying the substrate.

According to another embodiment of the present invention, the substrate processing method may further include performing apreliminary wet cleaning process of supplying a cleaning solution to the substrate before the dry cleaning process to clean the surface of the substrate, and drying the substrate.

According to another embodiment of the present invention, the preliminary wet cleaning process may include removing an organic material from the surface of the substrate, and the wet cleaning process may include removing fumes generated from an etching gas residue containing halogen compounds.

According to embodiments of the present invention, damage of a lower layer can be prevented, and a silicon oxide layer, an etching byproduct, and fumes can be efficiently removed from a substrate.

FIG. 2 is a top view schematically illustrating a state in which a trench is formed in a semiconductor substrate by an etching device, the semiconductor substrate is exposed to the atmosphere when being transferred to a dry cleaning device, and thus fumes are generated inside the trench.

FIG. 3 is a schematic configuration diagram of a substrate processing system according to an embodiment of the present invention.

FIG. 4 is a schematic configuration diagram of a wet cleaning module of FIG. 3.

FIG. 5 is a schematic configuration diagram of a dry cleaning module of FIG. 3.

FIG. 6 is a flowchart of a substrate processing method according to an embodiment of the present invention.

FIG. 7 is a flowchart of a substrate processing method according to another embodiment of the present invention.

Hereinafter, a substrate processing system and method according to embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 3 is a schematic configuration diagram of a substrate processing system according to an embodiment of the present invention. FIG. 4 is a schematic configuration diagram of a wet cleaning module of FIG. 3. FIG. 5 is a schematic configuration diagram of a dry cleaning module of FIG. 3.

Referring to FIGS. 3 to 5, a substrate processing system 1000 according to an embodiment of the present invention includes a cassette module 100, an atmospheric transfer module 200, a wet cleaning module 300, a loadlock module 400, a vacuum transfer module 500, and a dry cleaning module 600.

The cassette module 100 receives a substrate before and after processing. In the present embodiment, four cassette modules are arranged in one row, and two of the four cassette modules receive a substrate before processing, and the other two cassette modules receive a substrate after processing. Herein, as described below, processingdenotes a cleaning (or etching) process that is performed by the dry cleaning module 600 and the wet cleaning module 300.

The atmospheric transfer module 200 transfers a substrate that is placed in the cassette module 100, or transfers the substrate to the cassette module 100. The atmospherictransfer module 200 is connected to the four cassette modules and includes a transfer robot 210. The transfer robot 210 is movable along a direction in which the four cassette modules are arranged and transfers a substrate between a buffer part 220 and the cassette module 100.

The buffer part 220 temporarily receives a substrate and is disposed between a pair of wet cleaning modules 300 that will be described below. A substrate placed in the buffer part 220 is transferred to the wet cleaning module 300 or the loadlock module 400 by an assistant transfer robot 230. On the other hand, a substrate transferred from the wet cleaning module 300 and the loadlock module 400 is temporarily placed in the buffer part 220. Tothis end, a plurality of slots for receiving a substrate are prepared in the buffer part 220.

The wet cleaning module 300 cleans a substrate in a wet process. In the present embodiment, a pair of wet cleaning modules are provided. Referring to FIG. 4, the wet cleaning module 300 includes a chamber 310, a susceptor 320, and a cleaning solution sprayer 330. The susceptor 320 is rotatably disposed inside the chamber 310, and a substrate W is placed on the susceptor 320. The cleaning solution sprayer 330 is disposed at an upper portion of the susceptor 320 and supplies a cleaning solution to the substrate W. In this case, the cleaning solution may be changed appropriately according to the purpose of cleaning (i.e., a material that is intended to be removed from a substrate surface through cleaning). For example, the cleaning solution may be ultrapure water, deionized water, NH₄OH water, ozone water or the like. Also, the wet cleaning module 300 may further include a rinsing solution supplier that supplies a rinsing solution (for example, ultrapure) to a substrate for rinsing the substrate after cleaning. Alternatively, the wet cleaning module 300 may not include a separate rinsing solution supplier but rather allow the cleaning solution sprayer 330 to supply the rinsing solution.

By supplying the rinsing solution to a substrate and simultaneously rotating the susceptor 320, the rinsing solution is spread onto an entire surface of the substrate, thereby cleaning the substrate. Subsequently, the substrate is rinsed by supplying the rinsing solution to the substrate, and then the substrate is dried by continuously rotating the susceptor 320 for a certain time. At this point, the substrate may be heated or an inert gas may be supplied to the substrate for smooth drying. To this end, the wet cleaning module 300 may further include a heater (not shown) and an inert gas sprayer (not shown).

The amount of a cleaning solution (or rinsing solution) supplied to the substrate may be controlled such that the cleaning solution is spread only across a surface (top) of the substrate without flowing down the side surface or onto the bottom of the substrate. That is, by appropriately controlling the amount of cleaning solution in consideration of the rotation speed of thesubstrate, a centrifugal force according to the rotation speed, and a frictional force between the substrate and the cleaning solution, the cleaning solution spreads over the entire surface of the substrate and is thrown off the edge of the substrate by the centrifugal force, instead of flowing down the side surface at an edge of the substrate. In this way, by controlling the amount of cleaning solution, the cleaning solution is prevented from contacting the side surface and bottom of the substrate, and thus damage can be prevented from occurring in a lower layer of the substrate due to the cleaning solution.

Moreover, to prevent the cleaning solution from flowing down the side surface of the substrate, the wet cleaning module 300 may further include an assistant inert gas sprayer (not shown) that supplies an inert gas to the side surface of the substrate. When cleaning the substrate, by supplying the inert gas to the side surface of the substrate, the cleaning solution can be prevented from flowing down the side surface of the substrate.

In this case, by spraying the inert gas from a lower portion to an upper portion of the edgeof the substrate, the cleaning solution is not prevented from spreading across the entire top surface of the substrate due to the centrifugal force, and moreover, the cleaning solution can be efficiently prevented from flowing down the side surface of the substrate.

The loadlock module 400 changes pressure in a vacuum state and an atmosphericstate, and a cassette (not shown) for receiving a substrate is prepared inside the loadlock module 400.

The vacuum transfer module 500 transfers a substrate to the dry cleaning module 600 in the vacuum state andis connected to the loadlock module 400. The inside of the vacuum transfer module 500 is maintained in the vacuum state. Furthermore, a transfer robot 510 for transferring the substrate is prepared inside the vacuum transfer module 500. Herein, the transfer robot 510 may be a dual type transfer robot including two transfer arms, for enhancing transfer efficiency.

The dry cleaning module 600 cleans (or etches) a substrate in a dry process. In the present embodiment, four dry cleaning modules are provided. The four dry cleaning modules are disposed along the perimeter of the vacuum transfer module 500. Referring to FIG. 5, the dry cleaning module 600 includes a chamber 610 that is connected to the vacuum transfer module 500. A susceptor 620 with a substrate W disposed thereonis ascendably and descedably disposed at a lower side in an internal space of the chamber. The susceptor 620 may include a heat exchanger toadjust the temperature of the substrate. A shower head 630 that sprays a cleaning gas is disposed at an upper side in the internal space of the chamber 610 such that a silicon oxide layer and other impurities formed on the substrate W can be cleaned by a dry cleaning process.

The shower head 630 is connected to a gas supply system 640 for introducing a flux-controlled cleaning gas. In dry cleaning, HF gas is not used alone, but a mixed gas at least including HF gas is used as a cleaning gas. For example, a mixed gas of HF gas and NH₃ gas may be used as a cleaning gas. The gas supply system 640 is provided separately according to each component gas of the cleaning gas such that the component gases do not mix until they aresupplied into the chamber. That is, although not subdivided and shown, the gas supply system 640 includes a gas supply route 642 connected to a supply source 641 (canister containing gas bombe or liquid) for each component gas, and a mass flow controller (MFC) 643 included in the supply source 641.

The shower head 630 is a means for spraying a component gas which is received from the gas supply system 640 into the chamber 610. For efficientmaintenance and cleaning of the shower head 630, the shower head 630 may be a non-mixing type in which a cleaning gas does not mix inside the shower head 630 but rather mixes after it issprayed into the chamber 610. To this end, a dual type may be applied in which at least two separate flow paths are formed inside the shower head 630. A means for spraying a cleaning gas into the chamber 610 may be of a different type than a shower head,such as a gas nozzle or a gas spray plate, or a type in which each gas is introduced from a lower portion instead of an upper portion of the chamber 610.

Moreover, a halogen lamp for heating a substrate may be additionally disposed at an upper end portion of the chamber 610.

To describe a dry cleaning process, the pressure inside the chamber 610 is adjusted to 10 mTorr to 150 Torr, the temperature of the susceptor 160 is adjusted to 20 C degrees to 70 C degrees, and then the substrate W is loaded. The temperature of the susceptor 620 is selected within a range most suitable for a cleaning reaction of a cleaning gas, and the temperature of the susceptor 620 becomes the temperature of the substrate W. At this point, in order to preventcleaning gas condensation, a wall of the chamber 610 may be maintained at 50 C degrees to 10 C degrees, and the shower head 630 may also be maintained at 50 C degrees to 150 C degrees.

Then, flux-controlled HF gas is introduced from an HF gas supply system into the chamber 610, and simultaneously flux-controlled NH₃gas is introduced from a NH₃gas supply system into the chamber 610.

In this way, HF gas and NH₃ gas that have been separately introduced into the chamber 610 are sprayed into the chamber 610 through the shower head 630 and mixed. Thus, a silicon oxide layer and other impurities formed on the substrate W are etched by the mixed gas. Subsequently, the susceptor 620 is lifted to a position illustrated with a dashed line inFIG. 5, and an etching byproduct is removed by heating the substrate W at 80 C degrees to 200 C degrees with the halogen lamp.

By adding at least one inert gas selected from among N₂, Ar, and He to the cleaning gas, the cleaning gas may be used as a carrier gas. Also, a cleaning gas with IPA gas added thereto may be supplied. In this case, since IPA is a liquid at room temperature, it may be vaporized by appropriate bubbling or a vaporizer and thenintroduced.

Below, a substrate processing operation using the above-described substrate processing system will be described.

FIG. 6 is a flowchart of a substrate processing method M100 according to an embodiment of the present invention.

Referring to FIG. 6, a substrate awaiting processing is placed in the cassette module 100. In this case, as described above in the background section, the substrate may be etched with an etching gas including a halogen ingredient such as F, Cl, or Br, and thus become a substrate with a pattern formed therein. The substrate is transferred to the wet cleaning module 300 via the atmospheric transfer module 200 and the buffer part 220, and a preliminary wet cleaning process S10 is performed in the wet cleaning module 300.

To describe the preliminary wet cleaning process S10, first, by supplying a cleaning solution (for example, ozone water) while rotating the substrate in operation S11, the cleaning solution is spread across an entire surface of the substrate so that any organic material left on the substrate is removed. The substrate is rinsed by supplying ultrapure water (rinsing solution) thereto and then dried in operation S12, thereby completing the preliminary wet cleaning process. Then, the substrate is transferred to the dry cleaning module 600 via the buffer part 220, the loadlock module 400, and the vacuum transfermodule 500 in process S20, and a dry cleaning process S30 is performed in the dry cleaning module 600.

To describe the dry cleaning process S30, withthe temperature of the substrate maintained within a temperature range most suitable for a cleaning reaction (20 C degrees to 70 C degrees), by spraying a cleaning gas (HF, NH₃) onto the substrate in operation S31, a silicon oxide layer and other impurities are etched by reacting with the cleaning gas. Subsequently, the susceptor 320 is lifted and an etching byproduct is removed by heating the substrate at 80 C degrees to 200 C degrees in operation S32.

Subsequently, the substrate is again transferred to the wet cleaning module 300 in process S40, and a wet cleaning process S50 is performed in the wet cleaning module 300. The wet cleaning process S50 removes fumes from the substrate. As described above in the background section, when halogen ingredients (which are added into an etching gas in an etching process for forming a pattern on a substrate) such as F, Cl, and Br are left inside the trench 40 of the substrate and then exposed to the atmosphere, the halogen ingredients react with moisture in the atmosphere to form solid hydrates.

To describe the wet cleaning process S50, by supplying a cleaning solution(ultrapure water) while rotating the substrate, the cleaning solution is spread across the entire surface of the substrate and fumes are removed by reacting with the cleaning solution, in operation S51. Then, by drying the substrate in operation S52, the wet cleaning process S50 is completed.

When proceeding to a process after the wet cleaning process S50, for stability of the process, chemical oxide is sometimes required to be formed on the substrate. In this case, fumes are removed, and then by supplying a cleaning solution (which facilitates the formation of chemical oxide) such as ozone water or ammonia water to the substrate, chemical oxide is formed on the substrate (subsequently, a rinsing process may be performed), and then the substrate is dried.

Subsequently, when the substrate has been transferred from a wet cleaning device to the cassette module 100 in process S60, all cleaning processes for the substrate are completed, and the substrate proceeds to a subsequent process.

In the above-described present embodiment, most silicon oxide layers and other impurities on the substrate are removed by the dry cleaning process. Thus, as in a typical wet cleaning process, damage of a lower layer such as SOD or BPSG is prevented.

In the wet cleaning process, the substrate is not entirely etched (i.e., the cleaning solution reacts only with fumes, and does not react with the other portions), and fumes on the substrate are selectively removed. This prevents damage of the lower layer due to isotropic etching, unlike conventional technology. In this case, as described above, by appropriately adjusting the supply ofcleaning solution, the cleaning solution is prevented from flowing down the side surface and along the bottom of the substrate, thereby preventing damage of the lower layer.

That is, in the present embodiment, a substrate is etched by the dry cleaning process, and fumes are removed in the wet cleaning process. Accordingly, damage of a lower layer is prevented, and moreover, a silicon oxide layer, an etching byproduct, and fumes can be efficiently removed from the substrate.

When there is an organic material on a substrate, it may not be effectivelyremoved in the dry cleaning process. That is, the organic material and silicon oxide layer can remain on the substrate even after the dry cleaning process. However, in the present embodiment, any organic material on the substrate is removed by the preliminary wet cleaning process beforethe dry cleaning process is performed, thus cleaning the substrate more thoroughly.

FIG. 7 is a flowchart of a substrate processing method M200 according to another embodiment of the present invention.

Referring to FIG. 7, in the present embodiment, a dry cleaning process S110 is performed immediately without performing a preliminary wet cleaning process, and then a substrate transfer process S120, a wet cleaning process S130, and a substrate unloading process S140 are sequentially performed. According to the present embodiment, the preliminary wet cleaning process is not performed so that the total time taken for cleaning is reduced compared to the above-described embodiment. Thus, the substrate processing method M200 can improve efficiency over the substrate processing method M100 when a separate wet cleaning process is not required before the dry wet process (for example, when there are no foreign substances not dissolved by a cleaning gas on the substrate).

Although the present invention has been described with reference to a number of exampleembodiments thereof, it should be understood that numerous modifications and alternative embodiments can be devised by those skilled in the art without departing from the spirit and scope of this disclosure. More particularly, various variations and modifications are possible in the component parts and/or arrangements of the subject combination arrangement within the scope of the disclosure, the drawings and the appended claims.

Claims

A substrate processing system, comprising:

a wet cleaning module configured to supply a cleaning solution to a substrate to clean a surface of the substrate, and dry the cleaned substrate; and

a dry cleaning module configured to spray a cleaning gas onto the substrate to etch a silicon oxide layer formed on the substrate, the cleaning gas containing HF gas
The substrate processing system of claim 1, further comprising:

a cassette module configured to receive the substrate before or after processing the substrate

an atmospheric transfer module configured to transfer the substrate received in the cassette module;

a vacuum transfer module connected to the dry cleaning module and configured to transfer the substrate to the dry cleaning module in a vacuum state; and

a loadlock module connected to the vacuum transfer module and changing a pressure between an atmospheric state and the vacuum state.
The substrate processing system of claim 1, wherein the wet cleaning module comprises:

a susceptor into which the substrate is placed, the susceptor being rotatable and

a cleaning solution sprayer configured to supply a cleaning solution to a top surface of the substrate,

wherein the susceptor rotates when the cleaning solution is supplied to the top surfaceof the substrate, and in consideration of a centrifugal force which is generated by rotation of the susceptor, a supply amount of the cleaning solution is adjusted such that the cleaning solution supplied to the top surface of the substrate is prevented from flowing down a side surface of the substrate.
The substrate processing system of claim 1, wherein the wet cleaning module comprises:

a susceptor into which the substrate is placed, the susceptor being rotatable

a cleaning solution sprayer supplying a cleaning solution to a top surface of the substrate; and

an assistant inert gas sprayer configured to spray an inert gas to a side surface of the substrate such that the cleaning solution is prevented from flowing down the side surface of the substrate.
The substrate processing system of claim 4, wherein the inert gas is sprayed from a lower portion to an upper portion of an edge of the substrate.
A substrate processing method, comprising:

performing a dry cleaning process of spraying a cleaning gas containing HF gas onto a substrate to remove a silicon oxide layer formed on the substrate and

performing a wet cleaning process of supplying the cleaning solution to the substrate to clean a surface of the substrate, and drying the substrate.
The substrate processing method of claim 6, further comprising performing a preliminary wet cleaning process of supplying a cleaning solution to the substrate before the dry cleaning process to clean the surface of the substrate, and drying the substrate.
The substrate processing method of claim 7, wherein,

the preliminary wet cleaning process includes removing an organic material from the surface of the substrate, and

the wet cleaning process includes removing fumes generated from an etching gas residue containing halogen compounds.
The substrate processing method of claim 6, wherein in the wet cleaning process, the cleaning solution is supplied to a top surfaceof the substrate when the substrate is rotating and, in consideration of a centrifugal force which is generated by rotation of the substrate, a supply amount of the cleaning solution is adjusted such that the cleaning solution supplied to the top surface of the substrate is prevented from flowing down a side surface of the substrate.
The substrate processing method of claim 6, wherein the wet cleaning process includes spraying an inert gas to a side surface of the substrate such that the cleaning solution supplied to a top surface of the substrate is prevented from flowing down the side surface of the substrate.
The substrate processing method of claim 10, wherein the inert gas is sprayed from a lower portion to an upper portion of an edge of the substrate.