A low-stress silicon nitride deposition furnace tube and deposition method for wafer processing

Abstract

The present invention discloses a low-stress silicon nitride deposition furnace tube and a deposition method for wafer processing, and relates to the technical field of silicon nitride deposition processing. The low-stress silicon nitride deposition furnace tube for wafer processing includes an outer tube module, an inner tube module, a wafer boat, an air intake module and an exhaust module; the air intake module includes a first collecting pipe and a second collecting pipe, and the end of the first collecting pipe is provided with a plurality of first exhaust holes, and the end of the second collecting pipe is provided with a plurality of second exhaust holes. The present invention utilizes an air intake module to realize the injection of ammonia and dichlorosilane mixed gas, and the mixed gas is injected into the third cavity through the first exhaust hole at the end of the first collecting pipe and the second exhaust hole at the end of the second collecting pipe, and then flows into the second cavity radially, so that the mixed gas flows laterally in the gap between adjacent wafers to form a laminar flow, further improving the air flow stability, and finally improving the stress uniformity of the silicon nitride film.

Description

Technical Field

[0001] The invention relates to the technical field of silicon nitride deposition processing, and in particular to a low-stress silicon nitride deposition furnace tube for wafer processing and a deposition method. Background Art

[0002] Wafer refers to the silicon wafer used to make silicon semiconductor circuits. Its original material is silicon. The surface of the wafer is usually provided with low-stress silicon nitride as an insulating layer and / or structural layer. Wafer processing usually adopts low-pressure chemical vapor deposition process (LPCVD) to coat low-stress silicon nitride on the surface of the wafer.

[0003] The traditional low-pressure chemical vapor deposition process uses a low-pressure deposition vertical furnace. The low-pressure deposition vertical furnace cavity adopts a double-tube structure. The inner quartz tube is designed to be straight-through, and the outer quartz tube is designed to be closed at the top. The gas enters the inner cavity through a quartz nozzle fixed on the gas collecting flange for deposition reaction. After that, the exhaust gas flows into the gap between the inner and outer quartz tubes through the top of the inner quartz tube and is then discharged.

[0004] In traditional technology, the quartz nozzle is installed at the bottom of the inner quartz tube. Therefore, the ammonia content and deposition rate of the inner quartz tube gradually decrease from bottom to top, resulting in a larger stress on the silicon nitride film on the wafer surface at the bottom of the inner quartz tube and a smaller stress on the silicon nitride film on the top of the wafer surface. Therefore, considering the limit of the stress gap, traditional technology can usually only have a production efficiency of 15 to 20 wafers per furnace. Summary of the invention

[0005] In order to overcome the problem of "uneven distribution of ammonia in the inner cavity of the inner quartz tube, resulting in large stress differences in the silicon nitride film at different positions" existing in the above-mentioned background technology, the present invention provides a low-stress silicon nitride deposition furnace tube and deposition method for wafer processing.

[0006] The technical solution adopted by the present invention to solve the above technical problems is:

[0007] A low stress silicon nitride deposition furnace tube for wafer processing, comprising an outer tube module, an inner tube module placed in a first cavity of the outer tube module, a wafer boat placed in a second cavity of the inner tube module, an air intake module for injecting ammonia and dichlorosilane mixed gas, and an exhaust module for exhausting waste gas; the outer tube module comprises a first tube body, the inner tube module comprises a second tube body placed in the inner cavity of the first tube body; the side wall of the second tube body is provided with an arc plate arranged along a radial outward protrusion, and the inner side of the arc plate is provided with a third cavity connected to the second cavity; the outer wall of the arc plate is connected to the inner wall of the first tube body; the air intake module comprises an air intake pipe, a first gas collecting pipe and a second gas collecting pipe; the first gas collecting pipe and the second gas collecting pipe are both vertically placed in the third cavity; a plurality of first exhaust holes are provided at the end of the first gas collecting pipe, and a plurality of second exhaust holes are provided at the end of the second gas collecting pipe; the wafer boat comprises a clamping assembly, and a limit ring and a heat preservation base are respectively installed at the top and bottom ends of the clamping assembly; the clamping assembly comprises a first clamping rod group and a second clamping rod group; the first clamping rod group comprises a plurality of The first clamping rod is arranged in a sizing arc shape, and the second clamping rod group includes a plurality of second clamping rods arranged in a sizing arc shape; the sizing arc where the first clamping rod group is located is arranged concentrically with the sizing arc where the second clamping rod group is located; the first clamping rods at both ends of the first clamping rod group are respectively the first clamping rod a and the first clamping rod b, and the second clamping rods at both ends of the second clamping rod group are respectively the second clamping rod a and the second clamping rod b; the first clamping rod a and the second clamping rod a are arranged in an axisymmetric shape, and the first clamping rod b and the second clamping rod b are arranged in an axisymmetric shape; the straight-line distance between the first clamping rod a and the second clamping rod a is smaller than the straight-line distance between the first clamping rod b and the second clamping rod b; the first clamping rod a and the second clamping rod a are respectively arranged at the left and right sides of the arc plate; the first clamping rod and the second clamping rod are respectively fitted with the inner wall of the second tube body; the side wall of the first clamping rod and the side wall of the second clamping rod are respectively provided with clamping grooves for clamping wafers.

[0008] As a further optimization solution of the present invention, the opening direction of the clamping groove points to the center of the sizing arc where the first clamping rod group is located.

[0009] As a further optimization scheme of the present invention, a longitudinally arranged strip hole is opened on the side wall of the second tube body, and the strip hole and the arc plate are arranged on opposite side walls of the second tube body; the first cavity and the second cavity are connected through the strip hole.

[0010] As a further optimization scheme of the present invention, the top of the first collecting pipe is bent downward to form a first bending portion, and the first exhaust holes are arranged at equal intervals along the axis of the first bending portion; the top of the second collecting pipe is bent downward to form a second bending portion, and the second exhaust holes are arranged at equal intervals along the axial direction of the second bending portion; the first bending portion is located above the second bending portion, and the central axis of the first bending portion is arranged collinearly with the central axis of the second bending portion.

[0011] As a further optimization solution of the present invention, the side wall of the second tube body is provided with a plurality of inner recesses for occupying the turbulent space, the inner recesses are provided between adjacent first clamping rods, and the inner recesses are provided between adjacent second clamping rods.

[0012] As a further optimization solution of the present invention, the side walls of adjacent first clamping rods are arranged in contact with each other, and the side walls of adjacent second clamping rods are arranged in contact with each other, so as to occupy the turbulent flow space.

[0013] As a further optimization scheme of the present invention, the first clamping rod located between the first clamping rod a and the first clamping rod b is the first clamping rod c, and the second clamping rod located between the second clamping rod a and the second clamping rod b is the second clamping rod c, and the outer wall of the first clamping rod a, the outer wall of the first clamping rod c, the outer wall of the second clamping rod a and the outer wall of the second clamping rod c are respectively installed with first place-occupying fins arranged in a discontinuous manner, and the first place-occupying fins are used to occupy the turbulent space; a first movable gap is provided between the first place-occupying fins adjacent to each other in the longitudinal direction, and the first movable gap and the clamping groove are located at different heights, so that the first movable gap and the wafer are located at different heights.

[0014] As a further optimization scheme of the present invention, the exhaust module includes an exhaust pipe connected to the side wall of the first tube body; the side wall of the first tube body is provided with an exhaust port; the exhaust pipe is inserted into the exhaust port; and an electric control valve body is installed in the middle of the exhaust pipe.

[0015] As a further optimization scheme of the present invention, the insulation base includes a mounting shell connected to the clamping assembly and a plurality of bottom supporting fins arranged in a stacked manner under the mounting shell; it also includes an exhaust module, the exhaust module includes an exhaust pipe, the exhaust pipe is installed through the bottom of the side wall of the first tube body and the bottom of the side wall of the second tube body; the inner end opening of the exhaust pipe is at the same height as the bottom supporting fins located at the bottom layer; the outer end opening of the exhaust pipe is connected to an exhaust pump; the overall height of the first tube body is fixed, and a lifting platform is installed at the bottom end of the crystal boat.

[0016] A low-stress silicon nitride deposition method for wafer processing, which uses a low-stress silicon nitride deposition furnace tube for wafer processing to process the wafer, and the steps include: S1, the lifting platform drives the wafer boat downward, and then uses a mechanical arm to clamp the wafer and install it in the clamping groove; S2, the lifting platform drives the wafer boat upward until the wafer boat is inserted into the second cavity; S3, the electric control valve body is closed, and the first cavity 1101, the second cavity 2101 and the third cavity 2102 are evacuated by using the exhaust module 7; S4, preheated ammonia and dichlorosilane mixed gas is injected into the second cavity 2101 through the air intake module 4; after the mixed gas fills the second cavity 2101, the electric control valve body is opened to perform a silicon nitride deposition reaction; S5, after the silicon nitride deposition reaction is completed, the lifting platform drives the wafer boat downward, and then uses the mechanical arm to remove the wafer.

[0017] In summary, the present invention is beneficial in that:

[0018] The air intake module is used to realize the injection of ammonia and dichlorosilane mixed gas, and the mixed gas is injected into the third cavity through the first exhaust hole at the end of the first gas collecting pipe and the second exhaust hole at the end of the second gas collecting pipe, and then flows into the second cavity radially, so that the mixed gas flows laterally in the gap between adjacent wafers to form a laminar flow, further improving the air flow stability, and finally improving the stress uniformity of the silicon nitride film. The second tube body is provided with an arc plate, and the first clamping rod a and the second clamping rod a are respectively arranged at the left and right sides of the arc plate and fit with the inner wall of the second tube body, so that the airflow of the mixed gas is turned after hitting the first clamping rod a and the second clamping rod a and flows to the proximal position of the wafer, avoiding the mixed gas from flowing along the gap between the outer edge of the wafer and the inner wall of the second tube body, thereby improving the utilization rate of the mixed gas. The present invention has a stable structure, reliable function, convenient operation, and broad market prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present application is further described below with reference to the accompanying drawings:

[0020] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0021] Figure 2 It is a schematic diagram of the vertical section structure of the outer tube module and the inner tube module;

[0022] Figure 3 It is a cross-sectional top view of the structure of the present invention;

[0023] Figure 4 This is a schematic diagram of the crystal boat structure;

[0024] Figure 5 It is a schematic diagram of the position and structure of the clamping groove;

[0025] Figure 6 It is a schematic diagram of a cross-sectional top view of the first clamping rod group and the second clamping rod group;

[0026] Figure 7 It is a cross-sectional top view schematic diagram of the position and structure of the first clamping rod a and the second clamping rod a;

[0027] Figure 8 It is a schematic diagram of the side structure of the air intake module;

[0028] Fig. 9 is a schematic diagram of the position and structure of the first bending portion and the second bending portion;

[0029] Fig.10 It is a top view schematic diagram of the position of the turbulent space;

[0030] Fig.11 It is a schematic side view of the positions of the turbulent space a and the turbulent space b;

[0031] Fig.12 It is a schematic diagram of the cross-sectional top view of the inner concave part;

[0032] Fig.13 A top view schematic diagram of the location of the remaining space;

[0033] Fig.14 is a schematic top view of the position and structure of the first place-occupying fin and the second place-occupying fin;

[0034] Fig.15 is a schematic diagram of the relative positions of the first occupying fin and the first movable gap;

[0035] Fig.16 is a side view schematic diagram of the relative positions of the first place-occupying fin and the clamping groove;

[0036] Fig.17 is a schematic diagram of the bending stress state of the first occupying fin;

[0037] Fig.18 It is a top view schematic diagram of the second placeholder fin in an open state;

[0038] Fig.19 is a schematic diagram of the relative positions of the second occupying fin and the second movable gap;

[0039] Fig. 20 is a schematic diagram of the bending stress state of the second occupying fin;

[0040] Fig.21 is a side view schematic diagram of the relative positions of the second place-occupying fin and the clamping groove;

[0041] Fig. 22 Schematic diagram of the top view of the position and structure of the first limiting protrusion;

[0042] Fig.23 is a bottom view schematic diagram of the position and structure of the second limiting protrusion;

[0043] Fig.24 It is a schematic diagram of the location of the air extraction module;

[0044] Fig.25 This is a schematic diagram of the installation position of the lifting platform.

[0045] Description of reference numerals:

[0046] In the figure,

[0047] 1. outer tube module; 11. first tube body; 1101. first cavity; 12. bottom plate; 13. side support rod;

[0048] 2. Inner tube module; 21. Second tube body; 2101. Second cavity; 2102. Third cavity; 211. Arc plate; 212. Strip hole; 213. Inner concave portion;

[0049] 3. Crystal boat; 31. Clamping assembly; 310. Clamping groove; 311. First clamping rod group; 312. Second clamping rod group; 313. First place-occupying fin; 314. First movable gap; 315. Second place-occupying fin; 316. Second movable gap; 32. Limiting ring; 321. Second limit protrusion; 33. Mounting shell; 331. First limit protrusion; 332. Ventilation groove; 34. Bottom support fin; 35. Bottom support rod; 36. Bottom support plate;

[0050] 4. air intake module; 41. air intake pipe; 411. first air pipe; 412. second air pipe; 413. third air pipe; 414. fourth air pipe; 42. first air collecting pipe; 421. first bending portion; 422. first exhaust hole; 43. second air collecting pipe; 431. second bending portion; 432. second exhaust hole;

[0051] 5. Exhaust module;

[0052] 6. Wafer; 6a. Wafer a; 6b. Wafer b;

[0053] 7. Air extraction module;

[0054] 8. Lifting platform;

[0055] 311a, first clamping rod a; 311b, first clamping rod b; 311c, first clamping rod c;

[0056] 312a, second clamping rod a; 312b, second clamping rod b; 312c, second clamping rod c;

[0057] 21011, turbulent space; 21011a, turbulent space a; 21011b, turbulent space b;

[0058] 21012, remaining space. DETAILED DESCRIPTION

[0059] Based on the above structural features of the present application, the implementation methods of the present application are further described:

[0060] Reference Figure 1-2 The present embodiment provides a low stress silicon nitride deposition furnace tube for wafer processing, comprising an outer tube module 1, an inner tube module 2 placed in a first cavity 1101 of the outer tube module 1, a wafer boat 3 placed in a second cavity 2101 of the inner tube module 2, an air intake module 4 for injecting a mixed gas of ammonia and dichlorosilane, and an exhaust module 5 for exhausting waste gas. The mixed gas is injected into the second cavity 2101 through the air intake module 4, and then flows into the exhaust module 5 through the first cavity 1101 for silicon nitride deposition processing of the wafer 6.

[0061] Reference Figure 1 to Figure 3 The outer tube module 1 includes a first tube body 11 in a straight tube shape, and the inner tube module 2 includes a second tube body 21 placed in the inner cavity of the first tube body 11, and the second tube body 21 is in a straight tube shape. The second tube body 21 is fixedly installed in the first tube body 11. The side wall of the second tube body 21 is provided with an arc plate 211 arranged along the radial outward convexity (for example, a fixed connection is achieved by integral bending molding), and the inner side of the arc plate 211 is provided with a third cavity 2102 connected to the second cavity 2101; the outer wall of the arc plate 211 is connected to the inner wall of the first tube body 11 (for example, fixedly connected by bolts); the cross section of the first tube body 11 is generally circular; the cross section of the second tube body 21 is generally gourd-shaped.

[0062] Reference Figure 2 , Figure 3 , Figure 8-Figure 9 The air intake module 4 includes an air intake pipe 41, a first air collection pipe 42 and a second air collection pipe 43. The air intake pipe 41 is provided with four, namely, a first air pipe 411, a second air pipe 412, a third air pipe 413 and a fourth air pipe 414. The first air pipe 411, the second air pipe 412 and the first air collection pipe 42 are connected and communicated by a tee, and the third air pipe 413, the fourth air pipe 414 and the second air collection pipe 43 are connected and communicated by a tee. One of the first air pipe 411 and the second air pipe 412 is used to inject preheated ammonia, and the other is used to inject preheated dichlorosilane, so that the first air collection pipe 42 is filled with a mixed gas of ammonia and dichlorosilane. Similarly, one of the third air pipe 413 and the fourth air pipe 414 is used to inject preheated ammonia, and the other is used to inject preheated dichlorosilane, so that the second air collection pipe 43 is filled with a mixed gas of ammonia and dichlorosilane.

[0063] Reference Figure 2 , Figure 3 and Figure 8The four air inlet pipes 41 each include a horizontal pipe and a vertical pipe that are fixedly connected and communicated in an L-shape; the horizontal pipe and the vertical pipe are fixedly connected in an integrated manner. The horizontal pipe is installed through the bottom of the side wall of the first tube body 11 and the bottom of the side wall of the second tube body 21 (for example, fixedly connected by welding); the vertical pipe is vertically placed in the third cavity 2102, and the vertical pipe is fixedly connected to the inner wall of the arc plate 211 by welding or by a pipe clamp.

[0064] Reference Figure 8 and Fig. 9 The first gas collecting pipe 42 and the second gas collecting pipe 43 are both vertically placed in the third cavity 2102; the top and bottom ends of the first gas collecting pipe 42 are fixedly connected to the inner wall of the arc plate 211 by welding or by a pipe clamp; the second gas collecting pipe 43 is fixedly connected to the inner wall of the arc plate 211 by welding or by a pipe clamp. A plurality of first exhaust holes 422 are provided at the end of the first gas collecting pipe 42, and the first exhaust holes 422 are arranged at the position of the upper end of the first gas collecting pipe 42; a plurality of second exhaust holes 432 are provided at the end of the second gas collecting pipe 43, and the second gas collecting pipe 43 is arranged at the position of the upper end of the second gas collecting pipe 43. The first exhaust holes 422 are arranged in an equidistant linear array on the side wall of the first collecting pipe 42 along the axial direction of the first collecting pipe 42, and the second exhaust holes 432 are arranged in an equidistant linear array on the side wall of the second collecting pipe 43 along the axial direction of the second collecting pipe 43; the upper end of the first collecting pipe 42 is a sealed structure to avoid pressure relief at the upper end of the first collecting pipe 42, so that the mixed gas is discharged through the first exhaust holes 422; the upper end of the second collecting pipe 43 is a sealed structure to avoid pressure relief at the upper end of the second collecting pipe 43, so that the mixed gas is discharged through the second exhaust holes 432; the first exhaust holes 422 and the second exhaust holes 432 are both arranged horizontally to realize the horizontal discharge of the mixed gas, that is, the mixed gas flows into the second cavity 2101 along the radial direction of the second cavity 2101. Multiple wafers 6 are horizontally placed and stacked in the second chamber 2101. The mixed gas flowing radially along the second chamber 2101 flows laterally between adjacent wafers 6 to form a laminar flow, thereby improving the stability of the gas flow and the stress uniformity of the final silicon nitride film.

[0065] Reference Figure 2 to Figure 5 The wafer boat 3 includes a clamping assembly 31, and a limit ring 32 and a heat-insulating base are respectively installed at the top and bottom ends of the clamping assembly 31. The limit ring 32 and the heat-insulating base are used to prevent the top and bottom ends of the clamping assembly 31 from moving, thereby ensuring the clamping stability of the clamping assembly 31 on the wafer 6.

[0066] Reference Figure 3 to Figure 7The clamping assembly 31 includes a first clamping rod group 311 and a second clamping rod group 312; the first clamping rod group 311 includes a plurality of first clamping rods arranged in a sizing arc shape, and the second clamping rod group 312 includes a plurality of second clamping rods arranged in a sizing arc shape. The first clamping rod and the second clamping rod are both upright straight rod structures. The sizing arc where the first clamping rod group 311 is located is cocentrically arranged with the sizing arc where the second clamping rod group 312 is located, so as to adapt to the clamping installation of the circular wafer 6 and ensure the stability of the clamping of the wafer 6.

[0067] Reference Figure 3 and Figure 6-7 The first clamping rods at both ends of the first clamping rod group 311 are respectively the first clamping rod a311a and the first clamping rod b311b, and the second clamping rods at both ends of the second clamping rod group 312 are respectively the second clamping rod a312a and the second clamping rod b312b; the first clamping rod a311a and the second clamping rod a312a are arranged in an axisymmetric shape, and the first clamping rod b311b and the second clamping rod b312b are arranged in an axisymmetric shape; the straight-line distance H1 between the first clamping rod a311a and the second clamping rod a312a is smaller than the straight-line distance H2 between the first clamping rod b311b and the second clamping rod b312b. When in use, the wafer 6 is inserted / pulled out from between the first clamping rod b311b and the second clamping rod b312b.

[0068] Reference Figure 3 and Figure 7 Since the first clamping rod and the second clamping rod used to clamp the wafer 6 from the outside to the inside have a certain thickness, and the thickness of the first clamping rod and the second clamping rod at the clamping groove 310 is also not zero, a gap is inevitably generated between the outer edge of the wafer 6 and the inner wall of the second tube body 21. When the mixed gas flows horizontally along the direction of the gap, it cannot contact and react with the wafer 6, resulting in a decrease in the material utilization rate of the mixed gas. Therefore, the first clamping rod a311a and the second clamping rod a312a are respectively arranged at the left and right sides of the arc plate 211; the first clamping rod and the second clamping rod are respectively attached to the inner wall of the second tube body 21; that is, the first clamping rod a311a and the second clamping rod a312a are respectively attached to the inner wall of the second tube body 21, so that the airflow of the mixed gas hits the first clamping rod a311a and the second clamping rod a312a and then turns to flow to the proximal position of the wafer 6, thereby improving the material utilization rate of the mixed gas.

[0069] Reference Figures 4 to 6The first clamping rod side wall and the second clamping rod side wall are respectively provided with a clamping groove 310 for clamping the wafer 6. The opening direction of the clamping groove 310 points to the center of the sizing arc where the first clamping rod group 311 is located; or the opening direction of the clamping groove 310 points to the center of the sizing arc where the second clamping rod group 312 is located. The inner side wall of the clamping groove 310 is set in a circular shape and is adapted to the outer wall of the wafer 6 for clamping and installing the wafer 6, while avoiding damage to the wafer 6 caused by concentrated clamping force, thereby improving the yield rate.

[0070] Reference Figure 2 and Figure 3 , a longitudinally arranged strip hole 212 is opened on the side wall of the second tube body 21, and the strip hole 212 and the arc plate 211 are respectively arranged on the opposite side walls of the second tube body 21. For example, the strip hole 212 and the arc plate 211 are respectively arranged on the left and right side walls of the second tube body 21, and the connecting line between the strip hole 212 and the arc plate 211 coincides with the diameter direction of the second tube body 21, so that the mixed gas flows in a unidirectional manner along the diameter direction of the second tube body 21 as much as possible, reducing the generation of eddy currents, thereby depositing a silicon nitride film with more uniform stress.

[0071] Reference Figure 3 , the first cavity 1101 and the second cavity 2101 are connected through the strip hole 212. The mixed gas flows into the second cavity 2101 laterally through the third cavity 2102, and then flows into the first cavity 1101 through the strip hole 212. The height of the strip hole 212 is adapted to the height of the clamping assembly 31, for example, the height of the strip hole 212 is not less than 90% of the height of the clamping assembly 31, and the position of the top of the strip hole 212 is lower than the position of the top of the clamping assembly 31, and the position of the bottom of the strip hole 212 is higher than the position of the bottom of the clamping assembly 31, so as to ensure that the mixed gas can flow out smoothly through the strip hole 212.

[0072] Reference Figure 8 and Fig. 9, the top of the first gas collecting pipe 42 is bent downward to form a first bending portion 421, and the first exhaust holes 422 are arranged at equal intervals along the axis of the first bending portion 421; the top of the second gas collecting pipe 43 is bent downward to form a second bending portion 431, and the second exhaust holes 432 are arranged at equal intervals along the axial direction of the second bending portion 431; the first bending portion 421 is located above the second bending portion 431, and the central axis of the first bending portion 421 is arranged in a colinear manner with the central axis of the second bending portion 431. In the present invention, 100 to 150 wafers 6 are usually installed on a single wafer boat 3, so the second tube body 21 usually has a large aspect ratio (generally above 20:1); since the exhaust hole has a pressure relief effect, the farther the exhaust hole is from the gas injection end, the smaller the airflow outflow; when the pipeline is too long, the airflow outflowing from the exhaust hole far away from the gas injection end is not enough to support the deposition processing operation, so the present invention sets two gas collecting pipes (the first gas collecting pipe 42 and the second gas collecting pipe 43), thereby weakening the problem of airflow attenuation. The first exhaust holes 422 and the second exhaust holes 432 arranged in a straight line together form a complete exhaust structure, which has a smaller maximum-minimum airflow difference than a single air collecting pipe. Fig. 9 The first bent portion 421 is located above the second bent portion 431, and the first exhaust hole 422 arranged in a straight line and the second exhaust hole 432 arranged in a straight line are arranged in a collinear manner, thereby forming an exhaust structure with higher straightness, so that the mixed gas has higher uniformity when injected into the second cavity 2101, avoiding the eddy current and local flow unevenness caused by the exhaust holes arranged in a curved shape, and finally improving the uniformity of the stress of the silicon nitride film, improving product quality, and reducing the defective rate.

[0073] Reference Fig.10 and Fig.11 , the space formed by the outer wall of wafer 6, the inner wall of the second tube 21, and the adjacent first clamping rods forms a turbulent space 21011; the space formed by the outer wall of wafer 6, the inner wall of the second tube 21, and the adjacent second clamping rods forms a turbulent space 21011. For example, a turbulent space a21011a and a turbulent space b21011b are formed between the outer wall of wafer 6, the inner wall of the second tube 21, and the three second clamping rods. When wafer a6a is closer to the first exhaust hole 422 / the second exhaust hole 432 than wafer b6b, the mixed gas on the upper surface of wafer a6a has a faster flow rate and a smaller air pressure, so that the mixed gas on the upper surface of wafer b6b flows to the upper surface of wafer a6a through the turbulent space a21011a and / or the turbulent space b21011b, forming a turbulent phenomenon. Compared with turbulent flow, unidirectional laminar flow is more conducive to improving the uniformity of stress in silicon nitride films, so turbulent flow should be avoided as much as possible.

[0074] Reference Fig.12The side wall of the second tube body 21 is provided with a plurality of inner recesses 213 (for example, fixedly connected by integral bending molding) for occupying the turbulent space 21011. An inner recess 213 is provided between adjacent first clamping rods, and an inner recess 213 is provided between adjacent second clamping rods. The inner side wall of the inner recess 213 located between adjacent first clamping rods is adapted to the outer side wall of the wafer 6 and the outer side wall of the first clamping rod; the inner side wall of the inner recess 213 located between adjacent second clamping rods is adapted to the outer side wall of the wafer 6 and the outer side wall of the second clamping rod. The inner recess 213 is used to occupy the turbulent space 21011, thereby avoiding the occurrence of turbulent flow.

[0075] Reference Fig.13 , the side walls of adjacent first clamping rods are in contact with each other, and the side walls of adjacent second clamping rods are in contact with each other, so as to occupy the turbulent space 21011, thereby avoiding the occurrence of turbulent flow. When the cross-section of the first clamping rod and the second clamping rod is circular, the first clamping rod and the second clamping rod cannot completely occupy the turbulent space 21011, and a tooth-shaped residual space 21012 will be formed at the inner wall of the second tube body 21, but the adjacent first clamping rods are in contact with each other, the first clamping rod and the inner wall of the second tube body 21 are in contact with each other, the adjacent second clamping rods are in contact with each other, and the second clamping rod and the inner wall of the second tube body 21 are in contact with each other, so that the residual space 21012 is closed laterally, and the residual space 21012 is isolated. The top and bottom ends of the residual space 21012 are still open, but the residual space 21012 has a large aspect ratio, so the turbulent flow phenomenon is reduced to a relatively weak state.

[0076] Reference Figure 14 to Figure 16 The first clamping rod located between the first clamping rod a311a and the first clamping rod b311b is the first clamping rod c311c, and the second clamping rod located between the second clamping rod a312a and the second clamping rod b312b is the second clamping rod c312c. The outer wall of the first clamping rod a311a, the outer wall of the first clamping rod c311c, the outer wall of the second clamping rod a312a, and the outer wall of the second clamping rod c312c are respectively installed with first place-taking fins 313 arranged in a discontinuous manner (for example, through an integrated fixed connection or a bolted fixed connection), and the first place-taking fins 313 are arranged longitudinally. The first place-taking fins 313 are in an arc-shaped plate-like structure. Referring to Figure 4 , Figure 5 , Figure 6 and Fig.17 When the wafer 6 is clamped and installed, the first clamping rod and the second clamping rod need to bend resiliently, and the continuous first place-taking fin 313 has strong bending resistance. Therefore, the first place-taking fin 313 arranged in an intermittent manner is used to ensure the bendability of the first clamping rod a311a, the first clamping rod c311c, the second clamping rod a312a and the second clamping rod c312c.

[0077] Reference Figure 14 to Figure 16 The first place-taking fin 313 is used to occupy the turbulent space 21011, thereby avoiding the occurrence of turbulence. A first movable gap 314 is provided between the first place-taking fins 313 adjacent to each other in the longitudinal direction, and the first movable gap 314 is located at a different height from the clamping groove 310; when the wafer 6 is clamped in the clamping groove 310, the first movable gap 314 is located at a different height from the wafer 6, that is, the first place-taking fin 313 is provided on the lateral periphery of the wafer 6 instead of the first movable gap 314, thereby avoiding the occurrence of turbulence in the first movable gap 314.

[0078] Reference Fig.14 , Figure 18 to Figure 20 The first place-taking fins 313 are respectively arranged between the adjacent first clamping rods a311a and the first clamping rods c311c, between the two adjacent first clamping rods c311c, between the adjacent second clamping rods a312a and the second clamping rods c312c, and between the two adjacent second clamping rods c312c. The outer side wall of the first clamping rod b311b and the second clamping rod b312b are respectively installed with second place-taking fins 315 arranged in an intermittent manner (for example, through an integrated fixed connection or a bolted fixed connection), and the second place-taking fins 315 are arranged longitudinally. The second place-taking fins 315 are in the form of an arc plate. Similarly, the intermittently arranged second place-taking fins 315 are used to ensure the bendability of the first clamping rod b311b and the second clamping rod b312b. Refer to Fig.14 and Fig.18 The two second place-taking fins 315 extend away from the ends of the third cavity 2102 to the positions on both sides of the strip hole 212 respectively; the second place-taking fins 315 are used to reduce the turbulence phenomenon formed in the space surrounded by the first clamping rod b311b, the second clamping rod b312b, the outer wall of the wafer 6, and the inner wall of the second tube body 21, thereby improving the stress uniformity of the silicon nitride film finally formed.

[0079] Reference Figure 19 to Figure 21 , a second movable gap 316 is provided between the second place-taking fins 315 adjacent in the longitudinal direction. Similarly, the second movable gap 316 and the clamping groove 310 are located at different heights; when the wafer 6 is clamped in the clamping groove 310, the second movable gap 316 and the wafer 6 are located at different heights, that is, the second place-taking fins 315 are provided on the lateral periphery of the wafer 6 instead of the second movable gap 316, so as to avoid turbulence in the second movable gap 316.

[0080] Reference Fig.18 The first clamping rod b311b and the second clamping rod b312b are respectively rotatably connected to the mounting shell 33 (for example, connected by a bearing or plugged into a hole shaft). When the second occupying fin 315 is opened, the robotic arm can push the wafer 6 to be clamped and installed in the wafer boat 3 or pull the wafer 6 out of the wafer boat 3.

[0081] Reference Fig.14 , Figure 22-23 The top surface of the mounting shell 33 is fixed with a first limiting protrusion 331 by bolts, and the outer wall of the first limiting protrusion is adapted to the outer wall of the wafer 6 (for example, the outer wall of the first limiting protrusion is located 2-3 mm outside the outer wall of the wafer 6); the bottom surface of the limiting ring 32 is fixed with a second limiting protrusion 321 by bolts, and the outer wall of the second limiting protrusion is adapted to the outer wall of the wafer 6 (for example, the outer wall of the second limiting protrusion is located 2-3 mm outside the outer wall of the wafer 6). The first limiting protrusion 331 and the second limiting protrusion 321 are both used to prevent the second place-occupying fin 315 from rotating excessively, thereby preventing the second place-occupying fin 315 from squeezing the wafer 6 and damaging the wafer 6. When in use, the second place-occupying fin 315 is pushed / hooked by the robotic arm to achieve the closing / opening of the second place-occupying fin 315. Since the first clamping rod b311b and the second clamping rod b312b are elastic and the second place-taking fin 315 is arranged intermittently, the contact position between the robot arm and the second place-taking fin 315 should be as close as possible to the first limiting protrusion 331 / the second limiting protrusion 321 to minimize the deformation of the first clamping rod b311b, the second clamping rod b312b and the second place-taking fin 315, thereby protecting the wafer 6 from extrusion damage.

[0082] Reference Figure 2 and Figure 4 Since the first clamping rod and the second clamping rod are respectively fitted with the inner wall of the second tube body 21, and the first clamping rod and the second clamping rod are both longitudinally arranged, and the mounting shell 33 connects and supports the first clamping rod and the second clamping rod, the bottom ends of the first clamping rod and the second clamping rod are respectively provided with a reduced diameter portion, which is connected to the mounting shell 33 to prevent the outer wall of the mounting shell 33 from being located outside the outer wall of the first clamping rod / the outer wall of the second clamping rod.

[0083] Reference Figure 4The heat preservation base includes a mounting shell 33 connected to the clamping assembly 31 and a plurality of bottom support fins 34 arranged in a stacked manner below the mounting shell 33; the lower ends of the first clamping rod a311a, the first clamping rod c311c, the second clamping rod a312a, and the second clamping rod c312c are respectively fixedly connected to the upper surface of the mounting shell 33, and the lower ends of the first clamping rod b311b and the second clamping rod b312b are respectively rotatably connected to the upper surface of the mounting shell 33; the upper end of the first clamping rod and the upper end of the second clamping rod are respectively fixedly connected to the limit ring 32 by bolts. The heat preservation base also includes a bottom support rod 35 and a bottom support plate 36, the upper end of the bottom support rod 35 is fixedly connected to the lower surface of the mounting shell 33 by bolts, and the lower end of the bottom support rod 35 is fixedly connected to the bottom support plate 36 by bolts. A plurality of bottom support rods 35 are provided and arranged in a circular array, and the bottom support fins 34 are fixedly installed on the outer surface of the bottom support rod 35. When the wafer boat 3 is fully inserted into the second cavity 2101, the height of the first bent portion 421 and the height of the second bent portion 431 are both higher than the height of the mounting shell 33, so that the first exhaust hole 422 and the second exhaust hole 432 are as close to the wafer 6 as possible, while preventing the side wall of the mounting shell 33 from blocking the first exhaust hole 422 and the second exhaust hole 432.

[0084] Reference Figure 1 and Fig.24 The exhaust module 5 includes an exhaust pipe connected to the side wall of the first tube body 11; the side wall of the first tube body 11 is provided with an exhaust port; the exhaust pipe is plugged into the exhaust port; and an electric control valve body is installed in the middle of the exhaust pipe. The waste gas generated by the deposition reaction flows into the first cavity 1101 through the strip hole 212 and then discharged through the exhaust pipe.

[0085] Reference Figure 4 and Fig.24 The side wall of the mounting shell 33 is recessed inward to form a ventilation groove 332, and the ventilation groove 332 is located on the side of the mounting shell 33 close to the air intake module 4. The present invention also includes an exhaust module 7, which includes an exhaust pipe, which is installed through the bottom of the side wall of the first tube body 11 and the bottom of the side wall of the second tube body 21; the inner end opening of the exhaust pipe is at the same height as the bottom support fin 34 located at the bottom layer; the outer end opening of the exhaust pipe is connected to an exhaust pump. When the exhaust module 7 is turned on during the deposition process, the waste gas accumulated around the insulation base during the deposition reaction can be discharged to avoid excessive accumulation of waste gas and affect the deposition operation.

[0086] The ventilation groove 332 is located on a side of the mounting shell 33 close to the air intake module 4, and the air extraction pipe is located at a side wall position of the first tube body 11 / the second tube body 21 away from the air intake module 4. Fig.24For example, the mixed gas flows in through the ventilation groove 332 on the upper left and is extracted through the exhaust module 7 on the lower right. The mixed gas flows horizontally between the bottom support fins 34 and flows longitudinally at the side positions of the bottom support fins 34 to remove the ordinary air / exhaust gas accumulated around the insulation base as much as possible.

[0087] Reference Fig.25 , the overall height of the first tube body 11 is fixed. The first tube body 11 is fixedly installed in the inner cavity of the heating furnace, and ensures that when the wafer boat 3 is inserted into the second tube body 21, the clamping assembly 31 and the mounting shell 33 are completely placed in the inner cavity of the heating furnace. An electric drive lifting platform 8 is installed at the bottom of the wafer boat 3, and the electric drive lifting platform 8 and the heating furnace are respectively connected to an external power supply.

[0088] The air inlet module 4 also includes an air supply pipe, which is installed through the side walls of the first tube body 11 and the second tube body 21 and is connected to the second cavity 2101. The air supply pipe is used to inject supplementary gas (such as nitrogen) during the silicon nitride deposition reaction process, thereby improving product quality.

[0089] Reference Figure 4 and Figure 5 The clamping grooves 310 located on the same first clamping rod are arranged at equal intervals along the axial direction of the first clamping rod; the clamping grooves 310 located on the same second clamping rod are arranged at equal intervals along the axial direction of the second clamping rod.

[0090] Reference Figure 1 , Figure 2 and Figure 4 The top of the first tube body 11 is a sealing structure, and the top of the second tube body 21 is a sealing structure. The outer tube module 1 also includes a ring-shaped bottom plate 12, the outer edge of the bottom plate 12 is sealed and fixedly connected to the bottom end of the first tube body 11 (for example, connected by bolts and a sealing ring or by hot melt connection), and the inner edge of the bottom plate 12 is sealed and fixedly connected to the bottom end of the second tube body 21 (for example, connected by bolts and a sealing ring or by hot melt connection). The outer edge of the bottom support plate 36 is adapted to the inner edge of the bottom plate 12 to prevent air leakage.

[0091] Reference Figure 2 A side support rod 13 for connection and support is also provided between the first tube body 11 and the second tube body 21. The inner wall of the first tube body 11 and the side support rod 13 are fixedly installed by bolts, and the outer wall of the second tube body 21 and the side support rod 13 are fixedly installed by bolts.

[0092] A low stress silicon nitride deposition method for wafer processing, using a low stress silicon nitride deposition furnace tube for wafer processing to process a wafer 6, the steps comprising:

[0093] S1. The lifting platform 8 drives the wafer boat 3 downward until the wafer boat 3 is completely pulled out of the second tube body 21; the robot arm opens the second place-taking fin 315 (for example, by magnetic attraction, hooking, grasping, etc.), and then clamps and installs the wafers 6 one by one in the clamping groove 310; the robot arm closes the second place-taking fin 315 until the inner wall of the second place-taking fin 315 is in contact with the first limiting protrusion 331 and the second limiting protrusion 321.

[0094] S2 . The lifting platform 8 drives the wafer boat 3 upward until the wafer boat 3 is inserted into the second cavity 2101 .

[0095] S3, close the electric control valve body, and use the vacuum pump of the vacuum module 7 to evacuate the first cavity 1101, the second cavity 2101 and the third cavity 2102.

[0096] S4, inject preheated ammonia and dichlorosilane mixed gas (preheating temperature is 180-220 degrees Celsius) into the second cavity 2101 through the air intake module 4; after the mixed gas fills the second cavity 2101, open the electric control valve body, reduce the power of the air pump until gas is discharged from the air pump module 7 and the exhaust pipe (the critical value of the air pump power can be obtained by calculation or experiment), and perform silicon nitride deposition reaction. The air pump can discharge the waste gas accumulated around the insulation base, thereby improving the product quality of the wafer 6 located at the bottom.

[0097] S5. After the silicon nitride deposition reaction is completed, the lifting platform 8 drives the wafer boat 3 downward, and then the robot arm opens the second place-taking fin 315 to remove the wafer 6.

[0098] During step S4, the temperature of the silicon nitride deposition reaction is 700-720 degrees Celsius.

[0099] The present invention utilizes the air intake module 4 to realize the injection of the mixed gas of ammonia and dichlorosilane, and the mixed gas is injected into the third cavity 2102 through the first exhaust hole 422 at the end of the first gas collecting pipe 42 and the second exhaust hole 432 at the end of the second gas collecting pipe 43, and then flows into the second cavity 2101 along the radial direction, so that the mixed gas flows laterally in the gap between the adjacent wafers 6 to form a laminar flow, further improving the stability of the gas flow, and finally improving the stress uniformity of the silicon nitride film. The second tube body 21 is provided with an arc plate 211, and the first clamping rod a311a and the second clamping rod a312a are respectively arranged at the left and right sides of the arc plate 211 and fit with the inner wall of the second tube body 21, so that the gas flow of the mixed gas hits the first clamping rod a311a and the second clamping rod a312a and then turns to flow to the proximal position of the wafer 6, avoiding the mixed gas from flowing along the gap between the outer edge of the wafer 6 and the inner wall of the second tube body 21, thereby improving the utilization rate of the mixed gas. The present invention has a stable structure, reliable function, convenient operation, and broad market prospects.

[0100] In the description of the present invention, it should be noted that the directions or positional relationships indicated by the terms "up", "down", "left", "right", etc. are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention.

[0101] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection, it can be a mechanical connection, it can be an electrical connection, it can be a direct connection, it can be connected through an intermediate medium, and it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0102] To sum up, for those skilled in the art, according to the guidance of the present invention, without departing from the principles and spirit of the present invention, the changes, modifications, substitutions and deformations made to the present invention still fall within the protection scope of the present invention.

Claims

1. A low stress silicon nitride deposition furnace tube for wafer processing, characterized in that: It comprises an outer tube module (1), an inner tube module (2) disposed in a first cavity (1101) of the outer tube module (1), a crystal boat (3) disposed in a second cavity (2101) of the inner tube module (2), an intake module (4) for injecting a mixed gas of ammonia and dichlorosilane, and an exhaust module (5) for exhausting waste gas; The outer tube module (1) comprises a first tube body (11), and the inner tube module (2) comprises a second tube body (21) disposed in an inner cavity of the first tube body (11); a side wall of the second tube body (21) is provided with an arc plate (211) convexly arranged along a radial direction, and a third cavity (2102) communicating with the second cavity (2101) is provided on the inner side of the arc plate (211); the outer wall of the arc plate (211) is connected to the inner wall of the first tube body (11); The air intake module (4) comprises an air intake pipe (41), a first air collecting pipe (42) and a second air collecting pipe (43); the first air collecting pipe (42) and the second air collecting pipe (43) are both vertically arranged in the third cavity (2102); a plurality of first exhaust holes (422) are provided at the end of the first air collecting pipe (42), and a plurality of second exhaust holes (432) are provided at the end of the second air collecting pipe (43); The wafer boat (3) comprises a clamping assembly (31), and a limit ring (32) and a heat-insulating base are respectively installed at the top and bottom ends of the clamping assembly (31); the clamping assembly (31) comprises a first clamping rod group (311) and a second clamping rod group (312); the first clamping rod group (311) comprises a plurality of first clamping rods arranged in a sizing arc shape, and the second clamping rod group (312) comprises a plurality of second clamping rods arranged in a sizing arc shape; the sizing arc where the first clamping rod group (311) is located is cocentrically arranged with the sizing arc where the second clamping rod group (312) is located; The first clamping rods at both ends of the first clamping rod group (311) are respectively the first clamping rod a (311a) and the first clamping rod b (311b), and the second clamping rods at both ends of the second clamping rod group (312) are respectively the second clamping rod a (312a) and the second clamping rod b (312b); the first clamping rod a (311a) and the second clamping rod a (312a) are arranged in an axisymmetric shape, and the first clamping rod b (311b) and the second clamping rod b (312b) are arranged in an axisymmetric shape; the straight-line distance between the first clamping rod a (311a) and the second clamping rod a (312a) is smaller than the straight-line distance between the first clamping rod b (311b) and the second clamping rod b (312b); The first clamping rod a (311a) and the second clamping rod a (312a) are respectively arranged at left and right sides of the arc plate (211); the first clamping rod and the second clamping rod are respectively fitted with the inner wall of the second tube body (21); The first clamping rod side wall and the second clamping rod side wall are respectively provided with a clamping groove (310) for clamping a wafer (6); The first clamping rod located between the first clamping rod a (311a) and the first clamping rod b (311b) is a first clamping rod c (311c), and the second clamping rod located between the second clamping rod a (312a) and the second clamping rod b (312b) is a second clamping rod c (312c); the outer wall of the first clamping rod a (311a), the outer wall of the first clamping rod c (311c), the outer wall of the second clamping rod a (312a) and the outer wall of the second clamping rod c (312c) are respectively installed with first place-occupying fins (313) arranged in a discontinuous manner, and the first place-occupying fins (313) are used to occupy the turbulent space (21011); a first movable gap (314) is provided between the first place-occupying fins (313) adjacent to each other in the longitudinal direction, and the first movable gap (314) and the clamping groove (310) are located at different heights, so that the first movable gap (314) and the wafer (6) are located at different heights.

2. The low stress silicon nitride deposition furnace tube for wafer processing according to claim 1, characterized in that: The opening direction of the clamping groove (310) points to the center of the sizing arc where the first clamping rod group (311) is located.

3. The low stress silicon nitride deposition furnace tube for wafer processing according to claim 2, characterized in that: The side wall of the second tube body (21) is provided with a longitudinally arranged strip hole (212); the strip hole (212) and the arc plate (211) are arranged on opposite side walls of the second tube body (21); and the first cavity (1101) and the second cavity (2101) are connected via the strip hole (212).

4. The low stress silicon nitride deposition furnace tube for wafer processing according to claim 3, characterized in that: The top of the first air collecting pipe (42) is bent downward to form a first bent portion (421), and the first exhaust holes (422) are arranged at equal intervals along the axis of the first bent portion (421); the top of the second air collecting pipe (43) is bent downward to form a second bent portion (431), and the second exhaust holes (432) are arranged at equal intervals along the axial direction of the second bent portion (431); the first bent portion (421) is located above the second bent portion (431), and the central axis of the first bent portion (421) is arranged colinearly with the central axis of the second bent portion (431).

5. The low stress silicon nitride deposition furnace tube for wafer processing according to claim 4, characterized in that: The exhaust module (5) comprises an exhaust pipe connected to the side wall of the first tube body (11); the side wall of the first tube body (11) is provided with an exhaust port; the exhaust pipe is inserted into the exhaust port; and an electric control valve body is installed in the middle of the exhaust pipe.

6. The low stress silicon nitride deposition furnace tube for wafer processing according to claim 5, characterized in that: The heat-insulating base comprises a mounting shell (33) connected to the clamping assembly (31) and a plurality of bottom supporting fins (34) arranged in a stacked manner below the mounting shell (33); It also includes an air extraction module (7), the air extraction module (7) including an air extraction pipe, the air extraction pipe is installed through the bottom of the side wall of the first tube body (11) and the bottom of the side wall of the second tube body (21); the outer end opening of the air extraction pipe is connected to an air extraction pump; The overall height of the first tube body (11) is fixed, and a lifting platform (8) is installed at the bottom end of the crystal boat (3).

7. A method for depositing low stress silicon nitride for wafer processing, characterized in that: The wafer (6) is processed using the low stress silicon nitride deposition furnace tube for wafer processing as claimed in claim 6, the steps comprising: S1, the lifting platform (8) drives the wafer boat (3) downward, and then uses a mechanical arm to clamp and install the wafer (6) in the clamping groove (310); S2, the lifting platform (8) drives the wafer boat (3) upward until the wafer boat (3) is inserted into the second cavity (2101); S3, closing the electrically controlled valve body, and using the vacuum module (7) to evacuate the first cavity (1101), the second cavity (2101), and the third cavity (2102); S4, injecting preheated ammonia and dichlorosilane mixed gas into the second cavity (2101) through the gas intake module (4); after the mixed gas fills the second cavity (2101), opening the electric control valve body to perform a silicon nitride deposition reaction; S5. After the silicon nitride deposition reaction is completed, the lifting platform (8) drives the wafer boat (3) downward, and then uses a robotic arm to remove the wafer (6).

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