Apparatus and method for removing oxides and carbon from semiconductor films in single processing chamber

Abstract

A system and method for removing both carbon-based contaminants and oxygen-based contaminants from a semiconductor substrate within a single processing chamber is disclosed. The invention may include performing processing in the single processing chamber using a remote plasma unit and a plurality of gas sources.

Description

[0001] This application is a divisional application of the Chinese invention patent application filed on July 13, 2018 (application number: 201810768539.X, invention name: Apparatus and method for removing oxides and carbon from semiconductor films in a single processing chamber; applicant: ASM IP Holding Ltd.). Technical Field

[0002] The present disclosure relates generally to apparatus and methods for manufacturing electronic devices. More particularly, the present disclosure relates to removing oxides and carbon within semiconductor films formed in a processing chamber. Background Art

[0003] Before manufacturing semiconductor devices, it is desirable that the surface of the wafer or substrate be clean. Contamination on the substrate may adversely affect the mechanical and electrical properties of the formed semiconductor device. It is desirable to remove these contaminants before depositing a particular film onto the substrate.

[0004] Contaminants present on silicon or silicon germanium substrates may include carbon-based contaminants, such as carbon-containing contaminants and hydrocarbon contaminants. Other contaminants may include oxygen-based contaminants, such as native oxides. It may be necessary to remove these contaminants before the epitaxial process can begin.

[0005] Previous methods of contaminant removal have focused on removing one of the contaminants, either carbon-based or oxygen-based, but not both. This may be due in part to equipment limitations of previous methods. Therefore, systems and methods for removing both carbon-based and oxygen-based contaminants are desired. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] These and other features, aspects and advantages of the present invention disclosed herein are described below with reference to the drawings of certain embodiments, which are intended to illustrate and not to limit the present invention.

[0007] Figure 1 is a cross-sectional view of a system according to at least one embodiment of the present invention.

[0008] Figure 2 is a cross-sectional view of a system according to at least one embodiment of the present invention.

[0009] Figure 3A , Figure 3B and Figure 3C is a flow chart of a method according to at least one embodiment of the invention.

[0010] Figure 4 is a flow chart of steps in accordance with at least one embodiment of the invention.

[0011] Figure 5 is a flow chart of steps in accordance with at least one embodiment of the invention.

[0012] Figure 6 is a flow chart of steps in accordance with at least one embodiment of the invention. DETAILED DESCRIPTION

[0013] Although certain embodiments and examples are disclosed below, it should be understood by those skilled in the art that the present invention extends beyond the specifically disclosed embodiments and / or uses of the present invention as well as obvious modifications and equivalents thereof. Therefore, it is contemplated that the scope disclosed by the present invention should not be limited by the specific disclosed embodiments described below.

[0014] Embodiments of the present invention are directed to systems having a single processing chamber that has the capability to remove both carbon-based and oxygen-based contaminants. These embodiments have several advantages over previous approaches, including: (1) incorporating at least one remote plasma unit (RPU) having the capability to generate both hydrogen and fluorine radicals; and (2) the processing chamber is compatible with both hydrogen and fluorine radicals.

[0015] Embodiments of the present invention can be used to clean semiconductor substrates made of at least one of the following materials: for example, silicon, silicon germanium, or germanium. In one embodiment, the percentage of germanium in the silicon germanium can vary from 10% to 90%. Moreover, embodiments of the present invention can be used to etch carbon layers, such as advanced patterned films (APFs); photoresists; or other carbon contaminants, including CHFx, SiC, or SiOC. In addition, embodiments of the present invention can be used to clean the surface of dielectric materials, such as silicon oxide, silicon nitride, silicon oxynitride, silicon oxide fluoride, silicon carboxide, and silicon carboxynitride. In addition, embodiments of the present invention can be applied to patterned wafer surfaces.

[0016] Figure 1 A system 100 in accordance with at least one embodiment of the present invention is shown. The system 100 may include a reaction chamber 110, a pedestal 120, a showerhead 130, a remote plasma unit 140, and a transfer path 145 between the remote plasma unit 140 and the reaction chamber 110. A substrate 150 is placed on the pedestal 120 for processing.

[0017] The reaction chamber 110 defines a space for processing the substrate 150. The reaction chamber 110, the susceptor 120, the showerhead 130, and the transfer path 145 may be coated with a material or a bulk ceramic material to allow compatibility with different free radicals. The material used for coating may include at least one of the following: anodized aluminum (Al2O3); aluminum oxide formed by atomic layer deposition (ALD); plasma sprayed Al2O3; bare aluminum parts with natural aluminum oxide; yttrium oxide (Y2 O 3 ); yttria-stabilized zirconia (YSZ); zirconium oxide (ZrO 2 ); lanthanum zirconium oxide (LZO); yttrium aluminum garnet (YAG); yttrium oxyfluoride (YOF); combinations of the above materials; or the above substrates doped with other glassy phase materials. In some cases, the coating material can be made of two layers. For example, the first layer can be made of an anode Al 2 O 3 Coating, the second layer can be formed by ALD Al 2 O 3 Coating. The coating can be an amorphous phase, a crystalline phase, or a mixture. Bulk ceramic materials can include: aluminum oxide (Al 2 O 3 ); Zirconium oxide (ZrO 2 ); Yttrium oxide (Y 2 O 3 ); or yttria-stabilized zirconia (YSZ).

[0018] The system 100 may further include a first gas source 160, a second gas source 170, a third gas source 180, and a fourth gas source 190, all of which may provide gas to the remote plasma unit 140. For example, the remote plasma unit 140 may include a Paragon H* remote plasma unit available from MKS Instruments. The third gas source 180 may also be configured to provide gas directly into the reaction chamber 110 without passing through the remote plasma unit 140. For example, the first gas source 160 may include a precursor gas source that generates fluorine radicals, such as NF 3 CF 4 , C 2 F 6 , C 4 F 6 , C 4 F 8 、COF 2 , SF 6 or WF 6 For example, the second gas source 170 may include a gas source that generates hydrogen radicals, such as H 2 NH 3 or H 2 O. For example, the second gas source 170 may include a gas that generates oxygen radicals, such as oxygen or ozone. The third gas source 180 may be NH 3 For example, the fourth gas source 190 may be an inert gas source, such as argon, helium, nitrogen, or neon.

[0019] The remote plasma unit 140 generates free radicals provided from a gas source. The generated free radicals then pass through the showerhead 130 into the reaction chamber 110 and flow onto the substrate 150. The remote plasma source may include a ring-type ICP source or a coil-type ICP source driven by different RF frequencies, such as 400 kHz, 2 MHz, 60 MHz, and 2.56 GHz microwave sources.

[0020] Figure 2 A system 200 according to at least one embodiment of the present invention is shown. The system 200 may include a reaction chamber 210, a pedestal 220, a showerhead 230, a first remote plasma unit 240 dedicated to removing oxides with F*, a second remote plasma unit 245 dedicated to removing carbon with H*, a transfer path 246 below the first remote plasma unit, and a transfer path 247 below the second remote plasma unit. A substrate 250 is placed on the pedestal 220 for processing. The system 200 may also include a first gate valve 248 and a second gate valve 249.

[0021] The reaction chamber 210 defines a space for processing the substrate 250. The reaction chamber 210, the susceptor 220 and the showerhead 230 may be coated with a material or a bulk ceramic material to allow compatibility with different free radicals, such as anodized aluminum (Al 2 O 3 ); Aluminum oxide formed by atomic layer deposition (ALD); Al 2 O 3 ; Bare aluminum parts with natural aluminum oxide; Yttrium oxide (Y 2 O 3 ); yttria-stabilized zirconia (YSZ); zirconium oxide (ZrO 2 ); lanthanum zirconium oxide (LZO); yttrium aluminum garnet (YAG); yttrium oxyfluoride (YOF); combinations of the above materials; or the above substrates doped with other glassy phase materials. In some cases, the coating material can be made of two layers. For example, the first layer can be made of an anode Al 2 O 3 Coating, the second layer can be formed by ALD Al 2 O 3 Coating. The coating can be an amorphous phase, a crystalline phase, or a mixture. Bulk ceramic materials can include: aluminum oxide (Al 2 O 3 ); Zirconia (ZrO 2 ); Yttrium oxide (Y 2 O 3 ); or yttria-stabilized zirconia (YSZ). In addition to the above-mentioned coatings and bulk materials for different radicals, the material for the transport path 247 below the second remote plasma unit may also include bulk quartz material.

[0022] The system 200 may further include a first gas source 260, a second gas source 270, a third gas source 280, and a fourth gas source 290, all of which may provide gas to the first remote plasma unit 240 and the second remote plasma unit 245. The first remote plasma unit 240 and the second remote plasma unit 245 may include a ring-type ICP source or a coil-type ICP source driven by different RF frequencies, such as 400 kHz, 2 MHz, 60 MHz, and 2.56 GHz microwave sources. The third gas source 280 may also be configured to provide gas directly into the reaction chamber 210 without passing through the first remote plasma unit 240 or the second remote plasma unit 245. For example, the first gas source 260 may include a precursor gas source that generates fluorine radicals, such as NF3, CF4, C2F6, C4F6, C4F8, COF2, SF6, or WF6, etc. For example, the second gas source 270 may include a gas source that generates hydrogen radicals, such as H2, NH3, or H2O. For example, the second gas source 270 may include a gas that generates oxygen radicals, such as oxygen or ozone. The third gas source 280 may be NH 3 For example, the fourth gas source 290 may be an inert gas source, such as argon, helium, nitrogen, or neon.

[0023] The first remote plasma unit 240 (which may be dedicated to F* radicals) and the second remote plasma unit 245 (which may be dedicated to H* radicals) generate radicals provided from a gas source. The generated radicals then pass through the showerhead 230 into the reaction chamber 210 and flow onto the substrate 250. In order to prevent the radicals generated by one remote plasma unit from flowing back into the second remote plasma, gate valves 248 and 249 may be located at the outlet of the RPU.

[0024] Figure 3A A method according to at least one embodiment of the present invention is shown. The method includes an oxide conversion step 300, an oxide sublimation step 400, and a carbon removal step 500. Any one of these steps or any combination of these steps can be repeated as needed. The entire method can be repeated by repeating the cycle 600.

[0025] Figure 3B A method according to at least one embodiment of the present invention is shown. The method includes a carbon removal step 500, an oxide conversion step 300, and an oxide sublimation step 400. Any one of these steps or any combination of these steps can be repeated as needed. The entire method can be repeated by repeating the cycle 600. Figure 3B Methods and Figure 3A The difference is that the carbon removal step 500 is before the oxide conversion step 300.

[0026] Figure 3C A method according to at least one embodiment of the present invention is shown. The method includes a carbon removal step 500, an oxide conversion step 300, an oxide sublimation step 400, and a carbon removal step 500. Any one of these steps or any combination of these steps may be repeated as desired. The entire method may be repeated by repeating the cycle 600. Figure 3C Methods and Figure 3B The difference is that there is an additional carbon removal step 500 after the oxide sublimation step 400 .

[0027] According to at least one embodiment of the present invention, Figure 4 The oxide conversion step 300 is shown in FIG. The oxide conversion step 300 may include a step 310 of flowing a gaseous precursor into a remote plasma unit and a step 320 of flowing the generated free radicals and additional precursors onto the substrate. According to at least one embodiment of the present invention, step 310 may include flowing argon, hydrogen, and NF 3 Flow into the remote plasma unit. The argon flow rate can be in the range of between 0.01 and 20 slm, between 0.1 and 10 slm, or between 1 and 8 slm. The hydrogen flow rate can be in the range of between 10 sccm and 1500 slm, between 25 and 1200 slm, or between 50 sccm and 1000 slm. When the plasma is turned on in the remote plasma unit, the flow of NF3 can occur for a specific duration, ranging between 0.1 and 120 seconds, between 1 and 100 seconds, or between 5 and 80 seconds. Step 310 may include heating the reaction chamber 210 to a temperature between 5 and 120°C, between 5 and 80°C, or between 5 and 60°C.

[0028] As a result of step 310, fluorine radical gas is generated in the remote plasma unit. The fluorine radicals exit the remote plasma unit and may be combined with an optional additional precursor gas onto a substrate disposed in a reaction chamber in step 320. The optional additional precursor gas may include ammonia gas flowing at a rate between 10 sccm and 1500 slm, between 25 and 1200 slm, or between 50 sccm and 1000 slm. Step 320 may include heating the reaction chamber 210 to a temperature between 5 and 120° C., between 5 and 80° C., or between 5 and 60° C. The oxide conversion step 300 may result in a chemical reaction with an oxide on the silicon germanium substrate having an oxide as follows:

[0029]

[0030] As a result of the oxide conversion step 300, the oxide may be converted on the substrate into a solid ammonium hexafluorosilicate compound and a solid ammonium hexafluorogermanate compound.

[0031] According to at least one embodiment of the present invention, Figure 5 4. The oxide sublimation step 400 is shown in FIG. The oxide sublimation step 400 includes a first heating step 410 or a second heating step 420 or both. The first heating step 410 may include heating the substrate to a temperature above 125° C., above 100° C., or above 90° C. The result of the first step 410 may be the sublimation of a solid ammonium hexafluorosilicate compound according to the following reaction:

[0032]

[0033] The gaseous products may then be removed from the reaction chamber.

[0034] The second heating step 420 may include heating the substrate to a higher temperature than the first heating step 410. The temperature may be above 275°C, above 250°C, or above 225°C. To achieve high operating temperatures, the high temperature showerhead may be designed to heat to 250°C-300°C without heating the reaction chamber. The result of the second step 420 may be sublimation of the solid ammonium hexafluorogermanate compound according to the following reaction:

[0035]

[0036] The gaseous products may then be removed from the reaction chamber.

[0037] According to at least one embodiment of the present invention, Figure 6 5. The carbon removal step 500 is shown in FIG. The carbon removal step 500 includes a step 510 of flowing a hydrogen precursor and other gaseous precursors into a remote plasma unit and a step 520 of flowing the generated free radicals and optional additional precursors onto the substrate. The first heating step 510 may include flowing argon, hydrogen, and ammonia into the remote plasma unit. These gases may flow for a duration of between 0.1 seconds and 180 seconds, between 1 second and 120 seconds, or between 10 seconds and 90 seconds. As a result, hydrogen free radicals are generated in the remote plasma unit.

[0038] Step 520 reacts the generated hydrogen radicals with carbon-based contaminants in the substrate. This step may occur at a temperature between 25°C and 500°C, between 75°C and 400°C, or between 150°C and 300°C. A higher temperature showerhead may allow heating of the substrate and result in effective removal of carbon. The result of step 520 may be removal of carbon according to the following reaction:

[0039]

[0040] Other reactions may include the reaction of carbon with oxygen radicals. The gaseous products may then be removed from the reaction chamber.

[0041] The specific implementations shown and described are illustrative of the present invention and its best mode and are not intended to limit the scope of the various aspects and implementations in any way. In fact, for the sake of brevity, the conventional manufacturing, connection, preparation and other functional aspects of the system may not be described in detail. In addition, the connecting lines shown in the various figures are intended to represent exemplary functional relationships and / or physical connections between various elements. Many alternative or additional functional relationships or physical connections may exist in actual systems, and / or may not exist in some embodiments.

[0042] It should be understood that the configuration and / or method described herein are exemplary in nature, and these specific embodiments or examples are not considered to be restrictive because many variations are possible. The specific routine or method described herein can represent one or more of the various processing strategies. Therefore, the various actions shown can be performed in the order shown, performed in other orders, or can be omitted in some cases.

[0043] The subject matter of the present disclosure includes all novel and nonobvious combinations and sub-combinations of the various processes, systems and configurations, and other features, functions, acts, and / or properties disclosed herein, as well as any and all equivalents thereof.

Claims

1. A method for processing a semiconductor substrate, include: providing a reaction chamber and a susceptor configured to hold a substrate; performing an oxide conversion step on the substrate, the oxide conversion step comprising: (1) flowing a first gas into a first remote plasma unit to form a first radical gas; and (2) flowing the first radical gas and ammonia onto the substrate, wherein the first radical gas comprises fluorine radicals; After performing the oxide conversion step, performing an oxide sublimation step on the substrate, the oxide sublimation step comprising: (1) a first heating step, wherein the first heating step comprises heating the substrate to a temperature greater than 90°C; and (2) a second heating step, wherein the second heating step comprises heating the substrate to a temperature greater than 225°C; and performing a carbon removal step on the substrate; wherein the oxide conversion step, the oxide sublimation step, and the carbon removal step are each performed in the reaction chamber; and Any one of the oxide conversion step, the oxide sublimation step and the carbon removal step is repeated as needed.

2. The method according to claim 1, wherein the carbon removal step include: flowing a second gas into the first remote plasma unit to form a second radical gas; as well as flowing the second radical gas onto the substrate, The second radical gas includes hydrogen radicals.

3. The method according to claim 1, wherein the carbon removal step include: flowing a second gas into a second remote plasma unit to form a second radical gas; as well as flowing the second radical gas onto the substrate, The second radical gas includes hydrogen radicals.

4. The method according to claim 1, wherein the first gas comprises at least one of: NF 3 CF 4 , C 2 F 6 , C 4 F 6 , C 4 F 8 、COF 2 , SF 6 or WF 6 .

5. The method according to claim 2, wherein the second gas comprises at least one of: H 2 NH 3 , H 2 O, O 2 or 3 .

6. A method for processing a semiconductor substrate, include: providing a reaction chamber and a susceptor configured to hold a substrate; performing a carbon removal step on the substrate; performing an oxide conversion step on the substrate, the oxide conversion step comprising: (1) flowing a first gas into a first remote plasma unit to form a first radical gas; and (2) flowing the first radical gas and ammonia onto the substrate, wherein the first radical gas comprises fluorine radicals; performing an oxide sublimation step on the substrate, the oxide sublimation step comprising: (1) a first heating step, wherein the first heating step comprises heating the substrate to a temperature greater than 90°C; and (2) a second heating step, wherein the second heating step comprises heating the substrate to a temperature greater than 225°C; and wherein the carbon removal step, the oxide conversion step, and the oxide sublimation step are each performed in the reaction chamber; and Any one of the carbon removal step, the oxide conversion step and the oxide sublimation step is repeated as needed.

7. The method according to claim 6, wherein the carbon removal step include: flowing a second gas into the first remote plasma unit to form a second radical gas; as well as flowing the second radical gas onto the substrate, The second radical gas includes hydrogen radicals.

8. The method according to claim 6, wherein the carbon removal step include: flowing a second gas into a second remote plasma unit to form a second radical gas; as well as flowing the second radical gas onto the substrate, The second radical gas includes hydrogen radicals.

9. The method of claim 6, wherein the first gas comprises at least one of: NF 3 CF 4 , C 2 F 6 , C 4 F 6 , C 4 F 8 、COF 2 , SF 6 or WF 6 .

10. The method of claim 7, wherein the second gas comprises at least one of: H 2 NH 3 , H 2 O, O 2 or 3 .

Images