Inline filtration for steam applications

Abstract

To provide a method for selectively oxidizing a material of a substrate, which is a selective oxidation process using steam oxidation without introducing particle contaminants into an oxide layer.SOLUTION: In a method for selectively oxidizing a material of a substrate, according to the present invention: the substrate is disposed in a chamber; a hydrogen containing gas is introduced to the chamber, wherein the hydrogen containing gas is directed through a filter to the chamber, and wherein the filter is configured to filter particles greater than about 1 nm; the chamber is pressurized to a pressure of about 250 Torr to about 800 Torr while the hydrogen containing gas is maintained in the chamber; and the chamber is heated to a predetermined temperature for a predetermined period of time while the hydrogen containing gas is maintained in the chamber, and the substrate is selectively oxidized.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001]

[0001] Embodiments of the present disclosure relate generally to the field of semiconductor manufacturing, and more particularly, to methods and apparatus for the selective oxidation of composite silicon / metal films.

Background Art

[0002]

[0002] In the manufacture of semiconductor devices, the oxidation of silicon-containing substrates plays an important role. For example, in a standard semiconductor device, a gate oxide layer is typically located on a substrate that includes source regions, drain regions, and intervening silicon or polysilicon regions. Metal contacts are deposited over the source and drain regions, and a conductive layer is deposited over the gate oxide. The overall structure is often depicted as a stack of layers. When a voltage is applied across the gate oxide to create an electric field oriented along an axis from the substrate, through the gate oxide, to the conductive layer, the electrical properties of the region between the source and drain regions change, either allowing or stopping the flow of electrons between those regions. Thus, the gate oxide layer plays an important role in the structure of semiconductor devices.

[0003]

[0003] Unfortunately, the oxide layer can be damaged during processing, in which case the oxide layer can be repaired by re-oxidizing the device. Re-oxidation forms a thin layer of oxide on the sides of the gate oxide and underlying silicon-containing layer, repairing the edge damage. Since oxidizing other regions of the transistor can reduce conductivity and potentially damage the device, it is useful to oxidize only specific materials of the device. Selective oxidation, such as wet oxidation, dry oxidation, or steam oxidation, targets specific materials such as silicon or silicon oxides, while avoiding the oxidation of other materials.

[0004]

[0004] Unfortunately, vapor has a tendency to dissolve and / or transport particles through condensation and vaporization. Thus, vapor oxidation can introduce particles, such as dissolved organic particles, precursor particles, or particles of seals and / or sheet valves, into the device, which may impair the function of the device. Further, when the chamber pressure is high and the vapor ratio is high, particle contamination may increase, restricting the operating conditions of vapor oxidation.

[0005]

[0005] Accordingly, there is still a need for a selective oxidation process that uses vapor oxidation without introducing particulate contaminants into the oxide layer. SUMMARY OF THE INVENTION

[0006]

[0006] The present disclosure provides a method for selective oxidation of a substrate. The substrate is disposed within a chamber. A hydrogen-containing gas is introduced into the chamber. The hydrogen-containing gas is introduced into the chamber through a filter. The filter is configured to remove particles larger than about 1 nm. While maintaining the hydrogen-containing gas within the chamber, the chamber is pressurized to a pressure within the range of from about 250 Torr to about 800 Torr. While maintaining the hydrogen-containing gas within the chamber, the chamber is heated to a predetermined temperature over a predetermined time. The substrate is selectively oxidized.

[0007]

[0007] The present disclosure also provides a method for processing a substrate. The substrate is disposed within a rapid thermal processing (RTP) chamber. A non-reactive gas is introduced into the chamber. A hydrogen-containing gas is introduced into the chamber. The hydrogen-containing gas is introduced into the chamber through a filter. The filter is configured to remove particles larger than about 1 nm. While maintaining the hydrogen-containing gas within the chamber, the chamber is pressurized to a pressure higher than about 250. While maintaining the hydrogen-containing gas within the chamber, the chamber is heated to a processing temperature. The substrate is selectively oxidized.

[0008]

[0008] The present disclosure also provides a method for processing a substrate. The method includes at least a silicon-containing layer and a metal layer in a chamber. A hydrogen-containing gas is introduced into the chamber. The hydrogen-containing gas is introduced into the chamber through a filter. The filter is configured to remove particles larger than about 1 nm. While maintaining the hydrogen-containing gas in the chamber, the chamber is pressurized to a pressure higher than about 250 Torr. The silicon-containing layer is selectively oxidized.

[0009]

[0009] To enable a more detailed understanding of the above features of the present disclosure, a more specific description of the present disclosure, briefly summarized above, can be made by referring to the embodiments, some of which are shown in the accompanying drawings. However, since the present disclosure may admit other equally effective embodiments, it should be noted that the accompanying drawings illustrate only typical embodiments of this disclosure and should not be regarded as limiting the scope.

Brief Description of the Drawings

[0010]

Figure 1

[0010] It is a diagram of a rapid heating device according to multiple embodiments of the present disclosure.

Figure 2A

[0011] It is a diagram of a filtration module according to multiple embodiments of the present disclosure.

Figure 2B

[0012] It is a diagram of a heated filtration module according to multiple embodiments of the present disclosure.

Figure 3

[0013] It is a flowchart showing an embodiment of selective oxidation according to multiple embodiments of the present disclosure.

Figure 4A

[0014] It is a cross-sectional view of a substrate before applying a selective oxidation process according to an embodiment of the present disclosure.

Figure 4B

[0015] It is a cross-sectional view of a substrate after applying a selective oxidation process according to an embodiment of the present disclosure.

Figure 5

[0016] It is a graph showing the concentration of particles after vapor oxidation.

Figure 6

[0017] It is a graph showing the concentration of particles after vapor oxidation using a filtration module.

Figure 7

[0018] It is a graph showing the concentration of particles after vapor oxidation with or without using a filtration module.

Embodiments for Carrying Out the Invention

[0011]

[0019] The present disclosure describes a method for selectively oxidizing a silicon-containing material in a substrate using a filtration module. The filtration module can reduce the concentration of oxide layers and / or particles in the device and improve device performance. Further, the filtration module can be operated to prevent pressure drop. Thereby, the temperature and pressure of the vapor (e.g., hydrogen-containing vapor) introduced into the processing chamber are maintained to promote efficient vapor oxidation. The present disclosure will be described below with reference to a rapid heating chamber, but it should be understood that the present disclosure can be similarly implemented in one or more other chambers.

[0012]

[0020] FIG. 1 shows a rapid heating apparatus 100 that can be used to execute the process of the present disclosure. The apparatus features a process chamber 102 that can be evacuated or filled with a selected gas, as well as sidewalls 104 and a lower enclosure 106. The upper portion of the sidewalls is sealed against a light pipe assembly 108. From the light pipe assembly 108, radiant energy is directed into the chamber. The light pipe assembly 108 includes a plurality of tungsten halogen lamps 110, such as Sylvania EYT lamps, and each lamp is mounted within a light pipe 112. The light pipe 112 can be made of stainless steel, brass, aluminum, or other metals.

[0013]

[0021] Substrate 114 is supported within process chamber 102 by a support ring 116 that contacts an edge of the substrate. Support ring 116 is made of a material capable of withstanding high temperatures, such as silicon carbide, without imparting impurities to the substrate. Support ring 116 can be mounted on a rotating cylinder 118. In one embodiment, a quartz rotating cylinder capable of rotating the support ring and the substrate thereon can be used. Rotation of the substrate promotes a uniform temperature distribution.

[0014]

[0022] Process gas can be introduced into the chamber through a representative portal 120 and exhausted through a representative portal 122. In some embodiments, multiple gas supply portals and exhaust portals can be used. Temperature controller 124 receives measurements from pyrometer 126 and adjusts the power to lamp 110 to achieve uniform heating.

[0015]

[0023] A side inlet 128 can be fluidly coupled to process chamber 102. Side inlet 128 can include one or more nozzles or inlet ports or alternatively a showerhead for injecting one or more gases, such as hydrogen, steam, and / or oxygen. In one embodiment, side inlet 128 is fluidly coupled to a filtration module (not shown) described below with reference to FIG. 2. For example, the filtration module (not shown) can inject one or more gases through side inlet 128.

[0016]

[0024] Figure 2A shows the filtration module 200. The filtration module 200 may include a filter 202. The filter 202 may include stainless steel such as a stainless steel medium (e.g., mesh or wool). Through this stainless steel, the fluid is directed to facilitate filtration. The filter 202 may include a separator, mesh, or other size separation component suitable for separating particles or contaminants based on particle size. In one embodiment, the filter 202 may prevent particles having a size greater than 1 nm, e.g., greater than 1 nm, greater than 5 nm, greater than 10 nm, greater than 100 nm, greater than 1 μm, greater than 10 μm, greater than 100 μm, or greater than that from passing through the filter 202. Without being bound by theory, by preventing particles having a size of 1 nm or greater from passing through, a reduction in particle contaminants within the processing chamber (and thus on the substrate) may occur, which may improve device performance.

[0017]

[0025] In one embodiment, the filter 202 may include a pressure from about 400 Torr to about 600 Torr, e.g., from about 400 Torr to about 450 Torr, from about 450 Torr to about 500 Torr, from about 500 Torr to about 550 Torr, or from about 550 Torr to about 600 Torr. The filter 202 may result in a pressure drop from about 1 Torr to about 10 Torr, e.g., from about 1 Torr to about 3 Torr, from about 3 Torr to about 6 Torr, from about 6 Torr to about 9 Torr, or from about 7 Torr to about 10 Torr.

[0018]

[0026] Filter 202 can receive gas from carrier manifold 204. Carrier manifold 204 can direct one or more gases, such as steam, hydrogen, and / or oxygen, from valve manifold 206 to filter 202. Carrier manifold 204 can include any tube, casing, or flow path that can transfer one or more gases, such as hydrogen, steam, and / or oxygen, to filter 202. Carrier manifold 204 can include a pressure from about 400 Torr to about 600 Torr, such as from about 400 Torr to about 450 Torr, from about 450 Torr to about 500 Torr, from about 500 Torr to about 550 Torr, or from about 550 Torr to about 600 Torr.

[0019]

[0027] Carrier manifold 204 can receive one or more gases from valve manifold 206. Valve manifold 206 can include a plurality of valves, such as gate valves, butterfly valves, needle valves, diaphragm valves, pinch valves, check valves (non-return valves), plug valves, or combinations thereof. The plurality of valves can include one or more seal components and / or sheets to prevent the flow of gas to carrier manifold 204. In one embodiment, during operation, the plurality of valves can regulate and / or control the amount of one or more gases, such as steam, hydrogen, or oxygen, flowing into carrier manifold 204.

[0020]

[0028] FIG. 2A shows an exemplary embodiment of filtration module 200, but filtration module 200 can be adapted in any suitable manner. For example, filter 202 can be disposed downstream of valve manifold 206, such as between side inlet 128 and valve manifold 206. Alternatively, filter 202 can be disposed upstream of valve manifold 206 (not shown).

[0021]

[0029] In one embodiment, the filtration module 200 may include one or more sensors (not shown). For example, the one or more sensors may include a pressure sensor. As a further example, the one or more sensors may include a temperature sensor. In one embodiment, the one or more sensors may be disposed at any position within the filtration module 200.

[0022]

[0030] FIG. 2B shows a filtration module 200 including one or more heaters shown as heaters 208a, 208b, 208c, or 208d. In one embodiment, any of the side inlet, filter, carrier manifold, and / or valve manifold may be heated by heaters 208a, 208b, 208c, or 208d. The heaters raise the temperature of the filtration module 200 to a temperature within the range of from about 80° C. to about 140° C., for example, from about 80° C. to about 90° C., from about 90° C. to about 100° C., from about 100° C. to about 110° C., from about 110° C. to about 120° C., from about 120° C. to about 130° C., from about 130° C. to about 140° C. Without being bound by theory, heaters 208a-d may reduce condensation within the filtration module 200, thereby reducing the amount of dissolved contaminants in the one or more gases. In one example, heaters 208a, 208b, 208c, or 208d are resistance heaters or jackets that may be heated using a fluid.

[0023]

[0031] Figure 3 is a flowchart showing a method of selectively oxidizing a substrate according to the present disclosure. The first step in process 310 is to purge any reactive gas from the chamber. The purge avoids unwanted chemical reactions on the substrate during the preparation phase of the oxidation process where the temperature and pressure can be increased. The purpose of the present disclosure is to oxidize only the silicon-containing layer of a substrate that includes a silicon-containing layer, a metal layer, and optionally a barrier layer or a capping layer. To achieve this purpose, the gas composition within the process chamber can be controlled during any process step featuring an increased temperature or pressure. The purge is realized by pumping out all the gas from the chamber and then flowing a non-reactive gas into the chamber to create a non-reactive gas atmosphere within the process chamber. The non-reactive gas does not react with any substrate material during processing. The gas that is a non-reactive gas in the process of the present disclosure includes, without limitation, nitrogen gas (N 2 ), helium (He), argon (Ar), neon (Ne), and xenon (Xe).

[0024]

[0032] A substrate having a plurality of layers of a silicon-containing material, a metal, and optionally a barrier layer or a capping layer is placed within the chamber in the next step of process 312. The layers can be patterned to form device structures such as transistors on the substrate. FIG. 4A shows a typical gate transistor structure 400. A doped silicide region 402 is disposed within a polysilicon domain 404 of the substrate. The doped silicide region 402 forms the source and drain regions for the transistor. On top of the doped silicide region 402, a plurality of layers of polysilicon 406, gate oxide 408, barrier material 410, metal contact 412, and a protective material or hard mask material 414 can be deposited. Further, although not shown, the metal contact can be deposited directly on top of the doped silicide region with or without a barrier or nucleation layer in between. The process of the present disclosure selectively oxidizes only the polysilicon layer and the gate oxide layer, along with other silicon-containing areas of the substrate, without oxidizing the metal or other layers.

[0025]

[0033] The substrate can be introduced into the chamber through a slit valve in the process chamber. A transfer robot configured as part of a processing cluster or platform can be used to load the substrate into the chamber. Alternatively, a tray loader can be used together with a cartridge device for continuously loading and removing a plurality of substrates. Further, as part of a rotary processing cluster, a carousel arrangement can be used to transfer the substrate in and out of the process chamber, or a linear processing assembly can be used.

[0026]

[0034] Referring again to FIG. 3A, the substrate supported on the support ring in the process chamber under a non-reactive atmosphere then undergoes a temperature and pressure ramp-up step 314. Before ramping up the temperature and pressure, a hydrogen-containing gas, for example, vapor filtered through a filtration module, can be supplied to the process chamber through a side inlet. Alternatively, the non-reactive atmosphere can be maintained during the ramp-up by flowing a non-reactive gas inside and outside the process chamber. The pressure in the chamber can be precisely controlled, and as the temperature rises, any fugitive matter that may leak from the substrate can be removed by the flowing gas. The temperature and pressure can be ramped up simultaneously or continuously in any pattern to a desired predetermined process condition. The temperature ramp (slope) can be designed to provide the additional advantage of annealing any of the various layers of the substrate. For example, the pressure can be from about 150 Torr to about 800 Torr, such as from about 250 Torr to about 600 Torr, or from about 400 Torr to about 500 Torr. As a further example, the temperature can be higher than 700 °C, such as from about 800 °C to about 1000 °C, or from about 900 °C to about 1000 °C.

[0027]

[0035] Referring again to FIG. 3A, the hydrogen-containing gas, e.g., the vapor filtered through the filtration module, can be supplied to the process chamber before or after the temperature and pressure ramp-up in step 318. Without being bound by theory, water molecules diffuse into the crystal network of the silicon-containing material and can release hydrogen at Si—Si or Si—SiO 2 bonds. In step 320, the process continues until a predetermined end point, such as a specific amount of time, is reached. In step 322, the temperature is lowered and the chamber is evacuated to remove the reactive species. To complete the process, in step 324, an inert gas is supplied to the chamber again, and then in step 326, the substrate is removed.

[0028]

[0036] In another alternative embodiment, a hydrogen-containing gas, e.g., the vapor filtered from the filtration module, may be introduced into the chamber before reaching the desired temperature and pressure points, which has the potential advantage of passivating any metal layer on the substrate and further reducing the possibility of metal oxidation. In multiple other embodiments, an inert gas or a carrier gas may be used with the hydrogen-containing gas, e.g., the vapor filtered from the filtration module, and may be supplied separately or together with either gas. The gases may be mixed outside the reaction chamber or supplied to the chamber individually. The use of an inert gas can facilitate mixing and selectivity.

[0029]

[0037] The reaction is driven by the temperature and pressure within the reaction zone. The reaction zone is heated by convection from the hot substrate and the energy released from the oxidation reaction. Thus, the temperature required to drive the reaction is close to the substrate surface. In some embodiments, the reaction can be limited to a zone up to 1 cm from the substrate surface. Without being bound by theory, temperatures above 700° C. may help promote the selective oxidation reaction. In one embodiment, the temperature can be controlled by a sensor disposed within the chamber and connected to a temperature controller that varies the power to the heat lamp.

[0030]

[0038] In one embodiment, a hydrogen-containing gas is maintained within the processing chamber for a set amount of time. In one embodiment, for example, growth of a thin film of oxide on the silicon-containing material of the substrate can be achieved by about 20 angstroms to about 50 angstroms. For example, the set amount of time can include a duration of about 1 to about 5 minutes. FIG. 4B shows a device structure 420 after selective oxidation has been performed. The oxide layer 416 can grow adjacent to the silicon-containing layer of the structure. In the process of the present disclosure, an oxidation selectivity of polysilicon and silicon dioxide with respect to metallic tungsten of up to 99.6% is obtained. When the endpoint is reached, the temperature may be lowered, the reaction chamber may be pumped out, and a non-reactive gas may be supplied. The chamber may be purged for a short time to ensure that the reactive gas does not continue to potentially degrade the substrate, and then the substrate is removed from the chamber for further processing.

[0031]

[0039] Using the foregoing process, many silicon-containing materials on a substrate can be selectively oxidized with a reduced amount of particle contamination. Such silicon-containing materials include, but are not limited to, polysilicon (or polycrystalline silicon), doped silicon, microcrystalline silicon, doped microcrystalline silicon, amorphous silicon, doped amorphous silicon, common doped or undoped silicon, those not falling under any of the former labels, partially oxidized silicon materials substantially containing silicon dioxide (SiO 2 ) and combinations thereof. Similarly, many common metal conductors and barrier or protective layers can also safely undergo this process. Metal layer compositions that are not oxidized under such conditions include, but are not limited to, aluminum (Al), copper (Cu), tungsten (W), tungsten nitride (WN), titanium (Ti), titanium nitride (TiN), tantalum (Ta), tantalum nitride (TaN), tantalum carbonitride (TaCN), and combinations thereof.

[0032] Multiple examples

[0040] Next, referring to FIG. 5, the concentration of particulate contaminants was measured when the concentration of unfiltered vapor was varied. The particles were measured based on the 32 nm section. When the proportion of vapor exceeded 22% v / v of the side injection gas, the concentration of particulate contaminants exceeded an average of 200 particles. Further, as the proportion of vapor increased, the concentration of particles increased. For example, at 25% v / v of the side injection gas, the concentration of particulate contaminants increased to a maximum of 1400 particles.

[0033]

[0041] Next, referring to FIG. 6, the concentration of particulate contaminants was measured when the concentration of filtered vapor was varied. The particles were measured based on the 32 nm section. When the proportion of vapor was 22% v / v of the side injection gas, an average concentration of particulate contaminants of from about 7 to about 14 particles was produced. Further, as the proportion of vapor increased, the concentration of particulate contaminants was maintained below 15. For example, at 46% v / v of the side injection gas, the concentration of particulate contaminants was from about 2 to about 12 particles. Without being bound by theory, the filtered vapor enabled a reduction in particulate contaminants even when operating at higher vapor concentrations.

[0034]

[0042] Next, referring to FIG. 7, the concentration of particulate contaminants was measured using filtration modules disposed downstream and upstream of the valve manifold. The filtration module disposed downstream of the valve manifold produced a concentration of particulate contaminants of about 0 particles in the 32 nm section. Further, the filtration module disposed upstream of the valve manifold produced a concentration of particulate contaminants of about 0 particles in the 32 nm section. Alternatively, when no filtration module was implemented within the device 100, the concentration of particulate contaminants was from about 3500 to about 4300 particles in the 32 nm section. Without being bound by theory, the location of the filtration module upstream or downstream of the valve manifold can reduce the concentration of particulate contaminants and thereby improve device performance.

[0035]

[0043] Multiple embodiments of the present disclosure related to methods and apparatuses for selective oxidation of composite silicon / metal films have been described. The filtration module can reduce the concentration of oxide layers and / or particles within the device and improve device performance. Further, the filtration module can be operated to prevent pressure drop. Thereby, the temperature and pressure of the vapor introduced into the processing chamber are maintained to promote efficient vapor oxidation.

[0036]

[0044] While the foregoing is directed to multiple embodiments of the present disclosure, other and further embodiments of the present disclosure may be devised without departing from the basic scope thereof. The scope of the present disclosure is defined by the following claims.

Claims

1. 1. A method for selectively oxidizing a material of a substrate, comprising the steps of: placing the substrate in a chamber; introducing a hydrogen-containing gas into the chamber, the hydrogen-containing gas being directed into the chamber through a filter, the filter configured to remove particles larger than about 1 nm; pressurizing the chamber to a pressure in the range of about 250 Torr to about 800 Torr while maintaining the hydrogen-containing gas in the chamber; heating the chamber to a predetermined temperature for a predetermined time while maintaining the hydrogen-containing gas in the chamber; and selectively oxidizing the substrate.

2. The method of claim 1 , wherein the hydrogen-containing gas is steam.

3. The method of claim 1 , wherein the predetermined temperature is greater than about 700° C.

4. The method of claim 1 , wherein the filter is configured to remove particles larger than about 5 nm.

5. The method of claim 1 , wherein the filter comprises stainless steel.

6. The method of claim 1 , wherein the filter comprises one or more heaters.

7. The method of claim 6 , wherein the heater is configured to heat the filter to a temperature within a range of about 80° C. to about 140° C.

8. The method of claim 1 , wherein selectively oxidizing the substrate comprises oxidizing only silicon-containing materials.

9. The silicon-containing material may be silicon, doped silicon, polysilicon, doped polysilicon, amorphous silicon, doped amorphous silicon, microcrystalline silicon, doped microcrystalline silicon, silicon dioxide (SiO 2 9. The method of claim 8, comprising:

10. 10. The method of claim 1, wherein the filter contains a pressure in the range of about 400 Torr to about 600 Torr when directing the hydrogen-containing gas through the filter.

11. 10. The method of claim 1, further comprising: creating a pressure drop across the filter in a range of from about 1 Torr to about 10 Torr when directing the hydrogen-containing gas through the filter.

12. 1. A method for processing a substrate, comprising: placing the substrate in a rapid thermal processing (RTP) chamber; introducing a non-reactive gas into the chamber; introducing a hydrogen-containing gas into the chamber, the hydrogen-containing gas being directed into the chamber through a filter, the filter configured to remove particles larger than about 1 nm; pressurizing the chamber to a pressure greater than about 250 Torr while maintaining the hydrogen-containing gas in the chamber; heating the chamber to a processing temperature while maintaining the hydrogen-containing gas in the chamber; and selectively oxidizing the substrate.

13. The method of claim 12 , wherein the hydrogen-containing gas is steam.

14. The method of claim 12 , wherein the filter comprises stainless steel.

15. 13. The method of claim 12, wherein the filter comprises one or more heaters configured to heat the filter to a temperature within a range of about 80 degrees Celsius to about 140 degrees Celsius.

16. The method of claim 12 , wherein selectively oxidizing the substrate comprises oxidizing only silicon-containing materials.

17. 13. The method of claim 12, wherein the filter contains a pressure in the range of about 400 Torr to about 600 Torr when directing the hydrogen-containing gas through the filter.

18. 13. The method of claim 12, further comprising creating a pressure drop across the filter in a range of from about 1 Torr to about 10 Torr when directing the hydrogen-containing gas through the filter.

19. 1. A method for processing a substrate in a chamber, the substrate including at least a silicon-containing layer and a metal layer, the method comprising: introducing a hydrogen-containing gas into the chamber, the hydrogen-containing gas being directed into the chamber through a filter, the filter configured to remove particles larger than about 1 nm; pressurizing the chamber to a pressure greater than 250 Torr while maintaining the hydrogen-containing gas in the chamber; and selectively oxidizing the silicon-containing layer.

20. The method of claim 19 , wherein the hydrogen-containing gas is steam.

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