Chemical deposition furnace for depositing films

Abstract

To provide a chemical vapor deposition furnace by which layer quality uniformity of deposited layers over a wafer boat may be improved.SOLUTION: A chemical vapor deposition furnace for depositing silicon nitride films is disclosed. The furnace comprises a process chamber elongated in a substantially vertical direction, and a wafer boat for supporting a plurality of wafers in the process chamber. A process gas injector is provided inside the process chamber extending in a substantially vertical direction over substantially a wafer boat height and comprising a feed end connected to a source of a silicon precursor and a source of a nitrogen precursor and a plurality of vertically spaced gas injection holes to provide gas from the feed end to the process chamber. The furnace may comprise a purge gas injection system to provide a purge gas into the process chamber near a lower end of the process chamber.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to the field of semiconductor processing, and more specifically to a chemical vapor deposition furnace for depositing silicon nitride films. Background Art

[0002] Simultaneous processing of a plurality of semiconductor wafers in a vertical batch furnace presents a method problem of providing all wafers stacked in a wafer boat with substantially the same layer quality over the length of the wafer boat and over the wafer surface. To promote uniformity of layer quality, vertical furnaces are generally equipped with a boat rotation mechanism that rotates the wafer boat during processing to average out non-uniformity across the wafers.

[0003] A process condition for optimizing the uniformity of layer thickness deposited on wafers across the boat is temperature. To obtain a uniform layer thickness across the substrates of a batch of wafers in a wafer boat, each of these wafers may preferably be heated substantially uniformly to a carefully adjusted temperature by heating means arranged proximate to the side walls of the process chamber and proximate to the top wall of the process chamber.

[0004] It has been found that although adjusting the temperature across the boat may improve the uniformity of layer thickness across the boat, the quality of deposited layers across the boat may begin to exhibit variations. These variations may be undesirable. Summary of the Invention Problem to be Solved by the Invention

[0005] This “Summary of the Invention” is provided to introduce several selected concepts in a simplified form. These concepts are described in more detail in the “Modes for Carrying Out the Invention” of the exemplary embodiments of the present disclosure below. This Summary of the Invention is not intended to identify any major or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

[0006] The objective is to provide a chemical deposition furnace, which may improve the uniformity of the layer quality of the deposited layers across the wafer boat. [Means for solving the problem]

[0007] According to one embodiment, a chemical deposition furnace for depositing silicon nitride films may be provided. The furnace may comprise a tube defining a substantially vertically elongated process chamber and a wafer boat for supporting a plurality of wafers within the process chamber. The furnace may have a process gas injector inside the process chamber that extends substantially vertically beyond the height of the wafer boat and has a supply end that is connected in use to a first supply source for providing a silicon precursor and a second supply source for providing a nitrogen precursor. The process gas injector may be provided with a plurality of vertically spaced gas injection holes for supplying gas from the supply end to the process chamber. The furnace may have a purge gas injection system for supplying purge gas into the process chamber near the lower end of the process chamber.

[0008] According to a further embodiment, a method is provided for depositing a silicon nitride layer on a wafer, the method being The process involves providing multiple wafers in a wafer boat and loading the wafer boat substantially vertically into the process chamber of a chemical deposition furnace. The process involves supplying gas to the process chamber across wafers in a wafer boat by flowing a gas based on silicon and nitrogen precursors into a process gas injector through multiple vertically spaced gas injection holes, and This includes providing a purge gas into the process chamber near the lower end of the process chamber.

[0009] Various embodiments of the present invention may be applied separately or in combination. Embodiments of the present invention will be further illustrated in modes for carrying out the invention with reference to some of the examples shown in the drawings.

[0010] Naturally, the elements in the figures are illustrative for simplification and clarity and are not necessarily drawn to actual size. For example, the dimensions of some of the elements in the figures may be exaggerated relative to others to help improve understanding of the illustrated embodiments of this disclosure. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 shows a cross-sectional view of the tubes of a vertical process furnace. [Figure 2] Figure 2 schematically discloses a valve system, a purge gas injection system, and a control system for working in conjunction with the chemical deposition furnace shown in Figure 1. [Modes for carrying out the invention]

[0012] While certain embodiments and examples are disclosed below, it will be understood by those skilled in the art that the invention extends beyond the specifically disclosed embodiments and / or uses of the invention, as well as their obvious modifications and equivalents. Therefore, the scope of the disclosed invention is not intended to be limited by the specific disclosed embodiments described below. The figures presented herein are not meant to represent the actual appearance of any particular material, structure, or apparatus, but are merely idealized representations used to describe embodiments of the disclosure.

[0013] As used herein, the terms “substrate” or “wafer” may refer to any substrate material(s) on which devices, circuits, or films may be used. The term “semiconductor device structure” may refer to any part of a processed or partially processed semiconductor structure that is, includes, or defines at least a portion of the active or passive components of a semiconductor device formed on or within a semiconductor substrate.

[0014] Semiconductor substrates may be processed in batches in a vertical furnace. One example of such processing is the deposition of layers of various materials on the substrate. Part of the process may be based, for example, on chlorides and ammonia.

[0015] Figure 1 is a cross-sectional side view of an embodiment of a chemical deposition furnace, including a process tube 1 defining a process chamber 4. The furnace may include a vertically movable door 5 configured to support a wafer boat 6 configured to hold multiple substrates, and configured to close a central inlet opening 10 of the lower flange and / or upper flange 3. The upper and lower flanges 3 may partially close the open end of the process tube 1. A liner 2 may extend along the process tube 1 to protect the tube.

[0016] The door 5 may be provided with a drive unit 7 that enables the rotation of the wafer boat 6 within the process chamber 4. A pedestal 9 may be provided between the drive unit 7 and the wafer boat 6. The pedestal 9 may be provided with a heater and / or insulation to improve the thermal uniformity of the wafers within the boat 6. The liner 2 may be closed at the top, for example, using a dome shape, or it may be substantially closed at the bottom to gas above the opening. The lower flange 3 has an inlet opening 10 configured for inserting and removing the boat 6, which is configured to transport multiple substrates within the process chamber 4.

[0017] The process gas injector 17 may be located inside a process chamber 4 that extends substantially vertically beyond the height of the wafer boat 6. A liner 2 extending along the tube 1 may have an expansion section that extends radially outward to accommodate the process gas injector 17. The process gas injector 17 includes a supply end 18 operably connected to a first supply line 19, which may be connected to a first supply source of silicon precursor 20. The supply end 18 may also be operably connected to a second supply line 21, which may be connected to a second supply source containing nitrogen precursor 22.

[0018] The silicon precursor supplied at the supply end 18 of the process gas injector may contain silane. The silicon precursor may contain one or more compounds selected from the group consisting of monochlorosilane, dichlorosilane, trichlorosilane, tetrachlorosilane, disilane, and trisilane.

[0019] The nitrogen precursor supplied at the supply end 18 of the process gas injector may contain ammonia. The nitrogen precursor and silicon precursor may begin to mix and react with each other when they enter the process gas injector 17 at the supply end 18.

[0020] Figure 2 schematically discloses a valve system 31 for cooperating with the chemical vapor deposition furnace of Figure 1. Figure 2 shows that the supply end 18 (only partially shown) of the process gas injector 17 may be connected via a first supply line 19 and a second valve 37 to a second supply source 39 containing a nitrogen precursor 22. The supply end 18 of the process gas injector 17 may also be connected via a second supply line 21 and a first valve 35 to a first supply source 41 containing a silicon precursor 20. When both the first valve 35 and the second valve 37 are open for the silicon precursor 20 and the nitrogen precursor 22, the supply end 18 of the process gas injector 17 receives process gas for depositing a silicon nitride layer in the process chamber 4. It can be understood that a supply source means a container containing a precursor and / or gas, or a connection of a manufacturing plant that provides the precursor and / or gas.

[0021] A controller 50 operably connected to the valve system 31 may be provided. The controller 50 may control the first valve 35 and the second valve 37 during deposition. The controller 50 may be provided with a memory 51 and a processor 53. The controller 50 may be provided with a clock, for example as part of the processor 53 for executing a recipe according to time. The controller 50 may control the flow rate of the process gas into the process chamber 4 through the process gas injector 17 to be 100 to 500, preferably 250 standard cubic centimeters per minute (SCCM).

[0022] Returning to Figure 1, the process gas injector 17 may be provided with a plurality of vertically spaced gas injection holes 23 for uniformly providing the gas received inside the injector 17 at the supply end 18 to the process chamber 4 over the length of the wafer boat 6. The plurality of gas injection holes 23 may extend over a part of the height of the process gas injector 17. The first supply line 19 and the second supply line 21 may be partially provided as passages passing through one of the flanges 3, and further as tubes leading to a supply source of the nitrogen precursor 22 or the silicon precursor 20.

[0023] The plurality of gas injection holes may extend beyond part of the height of the process gas injector 17. Each of the gas injection holes 23 may have a gas injection hole diameter of at least about 1 mm. The diameter of the gas injection hole may be, for example, about 3 mm. All gas injection hole diameters of the process gas injector 17 may be substantially equal. Each gas injection hole may have a gas injection hole area, and the total area of all gas injection hole areas of the process gas injector 17 is at least about 30 mm 2 . The total area of all gas injection hole areas may be about 200 mm 2 to 400 mm 2 .

[0024] A chemical vapor deposition furnace may be provided with a purge gas injection system 45 constructed and arranged to supply purge gas 25 into the process chamber 4 near the lower end of the process chamber 4. It has been found that providing a flow of purge gas 25 into the process chamber 4 near the lower end of the process chamber may improve the uniformity of the quality of silicon nitride deposition on wafers across the height of the wafer boat 6. Quality uniformity may be controlled by measuring wet etch rate or refractive index from deposited layers on a plurality of wafers across the entire wafer boat 6. The plurality of gas injection holes 23 may extend beyond part of the height of the process gas injector 17, and the purge gas injection system 45 may be constructed and arranged to supply purge gas 24 below the lowest gas injection hole.

[0025] The tube 1 may be supported on a flange 3 having a central inlet opening 10 provided with a door 5 that may define an end of the processing chamber 4. The purge gas injection system 45 may be constructed and arranged to supply purge gas 25 above the door 5. The purge gas injection system 45 may be constructed and arranged to supply purge gas 25 at the height of the flange 3. The purge gas may be supplied through a passage in the flange 3.

[0026] A gas exhaust opening 8 may be provided in the chemical deposition furnace below the tube 1, and a purge gas injection system 45 may be constructed and arranged to provide purge gas 25 at the height of the gas exhaust opening 8. The purge gas injection system may be constructed and arranged to provide purge gas on a first side of the chemical deposition furnace, and the chemical deposition furnace may have a gas exhaust opening below the tube 1 on a second side not equal to the first side of the chemical deposition furnace. In this way, the immediate discharge of purge gas 25 through the gas exhaust opening 8 may be avoided.

[0027] The purge gas injection system 45 may be constructed and positioned to supply purge gas 25 into the process chamber 4 near the flange 3. Accordingly, the purge gas line 24 provided in the purge gas injection system 45 may be partially provided as a passage through one of the flanges 3 and further as a tube to the source of the purge gas 25.

[0028] Further details of the purge gas injection system 45 may be shown in Figure 2. The purge gas injection system 45 may be constructed and configured to provide an inert gas as the purge gas. The purge gas injection system 45 may be constructed and configured to provide nitrogen as the inert purge gas. Nitrogen is an inexpensive inert gas and readily available in manufacturing plants. It should be understood that the nitrogen precursor may not be nitrogen. The nitrogen precursor may be reactive, while nitrogen may not be reactive.

[0029] The purge gas injection system 45 may be provided with a purge valve 47 to control the flow of purge gas 25. The purge gas injection system 45 may be controlled by a controller 50. The purge gas injection system 45 may be controlled to supply 15 to 100, preferably 30 to 70, most preferably approximately 50 cubic centimeters per minute (SCCM) of purge gas into the process chamber 4. The purge gas injection system 45 may be constructed and arranged to supply an inert gas as purge gas near the lower end of the processing chamber 4 to improve the uniformity of the silicon nitride deposition quality on the wafer beyond the height across the wafer boat 6. The purge valve 47 of the purge gas injection system 45 may be controlled by a controller 50 to adjust the flow of purge gas in the processing chamber to adjust the uniformity of the silicon nitride deposition quality on the wafer beyond the height across the wafer boat 6.

[0030] The purge gas injection system 45 may optionally be provided with a process gas injector shortcut 33 constructed and arranged to also supply a silicon precursor and / or nitrogen precursor into the process chamber 4 at its lower end via the purge gas injection system 45. The silicon precursor and / or nitrogen precursor may be mixed with the purge gas 25.

[0031] Conversely, the process gas injector shortcut 33 may also be used to supply purge gas 25 into the process chamber 4 via the process gas injector 18. This purge gas may be mixed with a silicon precursor and a nitrogen precursor.

[0032] The chemical deposition furnace may be provided with a gas exhaust opening 8 at the lower end of the process chamber 4 for removing gas. In this way, a downward flow 26 may be generated within the process chamber 4 by closing the liner 2 above the liner opening for gas, supplying the process gas to the process chamber 4 using a process gas injector 17 and the purge gas 25 using a purge gas injection system, and removing the gas from the process chamber 4 at the lower end of the process chamber 4 by the gas exhaust opening 8. This downward flow may carry contaminants of reaction by-products, the substrate, the boat 6, the liner 2, and / or particles from the support area of ​​the liner 2 on the flange 3 downwards towards the gas exhaust opening 8 away from the processed substrate W. The gas exhaust opening 8 for removing gas from the process chamber 4 may be operably connected to a pump. The pump may be used to control the pressure within the process chamber 4 to a pressure of 20 to 500, more preferably 50 to 300, and most preferably 100 to 150 millitorres.

[0033] A chemical deposition furnace may be used to deposit a silicon nitride layer on a wafer W by providing multiple wafers in a wafer boat 6 and loading the wafer boat substantially vertically into the process chamber 4 of the chemical deposition furnace; supplying a process gas based on a silicon precursor 20 and a nitrogen precursor 22 to the process chamber 4 across the wafers in the wafer boat by flowing the process gas into a process gas injector 17 through multiple vertically spaced gas injection holes 23; and simultaneously supplying a purge gas 25 into the process chamber 4 near the lower end of the process chamber 4. The method may include measuring the uniformity of the silicon nitride deposition on the wafer beyond the height across the wafer boat 6 and adjusting the flow of the purge gas 25 into the process chamber 4 near the lower end of the process chamber to improve the uniformity of the silicon nitride deposition quality on the wafer beyond the height across the wafer boat. The pressure in the process chamber may be controlled to a pressure of 20 to 500, more preferably 50 to 300, and most preferably 100 to 150 millitorl.

[0034] The chemical deposition furnace may be equipped with heaters for heating the wafers in the wafer boat 6. The chemical deposition furnace may be equipped with a temperature measuring system mounted on the flange 3 and extending along the outer surface of the liner 2 toward the top of the liner for measuring the temperature. The temperature measuring system may include a beam having multiple temperature sensors arranged along the length of the beam to measure the temperature at different heights. The measured temperature may be used to control the heaters.

[0035] A preferred embodiment may be applicable to chemicals in which a chlorine precursor is used in combination with ammonia (NH3) as a nitrogen precursor. Examples of chlorine precursors include TICL4, SICL2H2, HFCL4, and ALCL3.

[0036] While exemplary embodiments of the present invention have been described above with partial reference to the accompanying drawings, it should be understood that the present invention is not limited to these embodiments. Variations of the embodiments of this disclosure can be understood and achieved by those skilled in the art who practice the claimed invention from a review of the drawings, disclosure, and the accompanying claims.

[0037] Throughout this specification, any reference to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in relation to an embodiment is included in at least one embodiment of the present invention. Therefore, the use of the phrase “in one embodiment” or “in an embodiment” in various places throughout this specification does not necessarily refer to the same embodiment. Furthermore, it should be noted that particular features, structures, or characteristics of one or more embodiments may be combined in any suitable manner to form new embodiments not expressly described.

Claims

1. A chemical vapor deposition furnace for depositing silicon nitride films, A tube that defines a process chamber that is essentially elongated vertically, A wafer boat for supporting multiple wafers within the process chamber, The process chamber comprises a process gas injector having a supply end that extends substantially vertically beyond the height of the wafer boat and is connected in use to a first supply source for providing a silicon precursor and a second supply source for providing a nitrogen precursor, and a plurality of vertically separated gas injection holes for supplying gas from the supply end to the process chamber, The chemical deposition furnace is equipped with a purge gas injection system near the lower end of the process chamber for supplying purge gas into the process chamber, A chemical deposition furnace, wherein the chemical deposition furnace is provided with a gas exhaust opening below the tube, and the purge gas injection system is constructed and arranged to supply the purge gas at substantially the same height as the gas exhaust opening.

2. The chemical deposition furnace according to claim 1, wherein the plurality of gas injection holes are formed above the supply end, and the purge gas injection system is constructed and arranged to provide the purge gas below the lowest gas injection hole.

3. The chemical deposition furnace according to claim 1, wherein the tube is supported on a flange having a central inlet opening provided with a door, and the purge gas injection system is constructed and arranged to provide the purge gas above the door.

4. The chemical deposition furnace according to claim 1, wherein the tube is supported on a flange, and the purge gas injection system is constructed and arranged to provide the purge gas at substantially the same height as the flange.

5. The chemical deposition furnace according to claim 1, wherein the tube is supported on a flange, and the purge gas injection system is constructed and arranged to supply the purge gas through a passage within the flange.

6. The chemical deposition furnace according to claim 1, wherein the purge gas injection system is constructed and arranged to provide the purge gas on a first side of the chemical deposition furnace, and the chemical deposition furnace is provided with a gas exhaust opening below the tube on a second side different from the first side of the chemical deposition furnace.

7. The chemical deposition furnace according to claim 1, wherein the purge gas injection system is connected to a purge gas supply source.

8. The chemical deposition furnace according to claim 7, wherein the purge gas injection system is constructed and arranged to provide an inert gas as the purge gas.

9. The chemical deposition furnace according to claim 8, wherein the purge gas injection system is constructed and arranged to provide nitrogen as the purge gas.

10. The chemical deposition furnace according to claim 1, wherein the purge gas injection system is constructed and arranged to supply 15 to 100 cubic centimeters per minute (SCCM) of purge gas into the process chamber.

11. The chemical deposition furnace according to claim 10, wherein the purge gas injection system is constructed and arranged to supply 30 to 70 cubic centimeters per minute (SCCM) of purge gas into the process chamber.

12. The chemical deposition furnace according to claim 1, wherein the purge gas injection system is constructed and arranged to also provide silicon and nitrogen precursors into the process chamber near the lower end of the process chamber.

13. The chemical deposition furnace according to claim 7, wherein the purge gas injection system is constructed and arranged to supply an inert gas as a purge gas into the process chamber in order to improve the uniformity of silicon nitride deposition on the wafer beyond the height of the wafer boat.

14. The chemical deposition furnace according to claim 1, wherein the first supply source comprises silane as the silicon precursor.

15. The chemical vapor deposition furnace according to claim 1, wherein the first supply source comprises one or more compounds selected from the group consisting of monochlorosilane, dichlorosilane, trichlorosilane, tetrachlorosilane, disilane, and trisilane as the silicon precursor.

16. The chemical deposition furnace according to claim 1, wherein the second supply source contains ammonia as the nitrogen precursor.

17. The chemical deposition furnace according to claim 1, wherein the gas flow entering the process chamber through the process gas injector is 100 to 1,000 meters per minute (SCCM).

18. A method for depositing a silicon nitride layer on a wafer using the chemical deposition furnace described in Claim 1, The process involves providing multiple wafers in a wafer boat and loading the wafer boat substantially vertically into the process chamber of a chemical deposition furnace. A gas based on silicon precursors and nitrogen precursors is injected into a process gas injector through multiple vertically spaced gas injection holes, and the gas is supplied to the process chamber across the wafers in the wafer boat. A method comprising supplying a purge gas into the process chamber near the lower end of the process chamber.

19. A method for depositing a silicon nitride layer on a wafer, To measure the uniformity of silicon nitride deposition on the wafer that exceeds the height across the wafer boat, The method according to claim 18, comprising adjusting the flow of purge gas into the process chamber near the lower end of the process chamber to improve the uniformity of the silicon nitride deposition on the wafer beyond the height across the wafer boat.

20. A method for depositing a silicon nitride layer on a wafer, The method according to claim 18, comprising controlling the pressure in the process chamber to a pressure of 20 to 500 millitorl.

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