Wafer manufacturing method and semiconductor integrated circuit chip

Abstract

The invention discloses a wafer manufacturing method and a semiconductor integrated circuit chip, and the method comprises the steps: providing a substrate, and feeding the substrate into a furnace tube; forming a front surface film layer on the substrate, and synchronously forming a back seal comprising at least one back surface film layer by utilizing the formation of the front surface film layer; rotating the substrate so that the contact positions of the wafer and the furnace tube are not overlapped; the rotation comprises first-time rotation and second-time rotation, and the back seal meeting the first preset requirement is formed through at least two times of rotation. And after the furnace tube process is finished, each part of the back surface of the substrate can be protected by the back film layer, so that particle pollution is not easy to generate in the subsequent process.

Description

Technical Field

[0001] The present invention relates to the field of semiconductors, and particularly to a method for manufacturing a wafer and a semiconductor integrated circuit chip. Background Art

[0002] In the manufacturing process of a CMOS image sensor (CIS), in order to prevent elements such as boron and phosphorus or metal ions in the substrate from falling off the back surface of the substrate and affecting product performance, a thin film is usually grown on the back surface of the substrate as a back seal. However, the cost of this process is relatively high.

[0003] In order to reduce costs, in actual production, "wafer without back seal" is used, that is, by forming a film layer on the front surface of the substrate, a back film layer is synchronously formed on the back surface of the substrate, and this back film layer is used as the back seal of the wafer. When the substrate is placed on the boat feet in the furnace tube process, a part of the back surface of the substrate will be blocked by the boat feet and the back film layer cannot be formed. In subsequent processes, the silicon element of this part of the substrate is exposed without the protection of the back film layer and is prone to particle contamination. Summary of the Invention

[0004] The purpose of the present invention is to solve the problem that a part of the back surface of the substrate is blocked by the boat feet and the back film layer cannot be formed, resulting in the exposure of a part of the back surface of the substrate and being prone to particle contamination in subsequent processes.

[0005] To achieve the above purpose, the present invention provides a method for manufacturing a wafer, including:

[0006] Providing a substrate and feeding the substrate into a furnace tube;

[0007] Forming a front film layer on the substrate, and synchronously forming a back seal including at least one back film layer by using the formation of the front film layer;

[0008] Rotating the substrate to make the contact position between the wafer and the furnace tube non - coincident;

[0009] The rotation includes a first rotation and a second rotation. Through at least two rotations, a back seal meeting the first preset requirement is formed.

[0010] Optionally, the rotation further includes a third rotation. Through at least three rotations, a back seal meeting the second preset requirement is formed.

[0011] Optionally, the rotation further includes a fourth rotation. The third rotation and the fourth rotation occur in the same back film layer to form a back seal meeting the third preset requirement.

[0012] Optionally, the back film layer includes a silicon nitride film layer and / or a backside high-temperature oxide film layer; the rotation occurs before the formation of the silicon nitride film layer and / or the backside high-temperature oxide film layer starts; and / or the rotation occurs during the formation of the silicon nitride film layer.

[0013] Optionally, the back film layer includes a first oxide film layer and a first silicon nitride film layer adjacent to the substrate in sequence. The first rotation occurs before the formation of the first silicon nitride film layer, and the second rotation occurs during or after the formation of the first silicon nitride film layer.

[0014] Optionally, the rotation occurs during the formation of the first silicon nitride film layer, and a rotation occurs immediately after the formation of the first silicon nitride film layer.

[0015] Optionally, the directions of adjacent rotations are opposite, and the angles of adjacent rotations are the same or different.

[0016] Optionally, the direction of the first rotation is opposite to that of the second rotation, and the angles are the same.

[0017] Optionally, the directions of adjacent rotations are the same, and the angles of adjacent rotations are the same or different.

[0018] Optionally, on the side of the first silicon nitride film layer away from the substrate, the back film layer further includes a second silicon nitride film layer adjacent to the first silicon nitride film layer, and the third rotation occurs before the formation of the second silicon nitride film layer.

[0019] Optionally, the fourth rotation occurs during the formation of the second silicon nitride film layer.

[0020] Optionally, between the first silicon nitride film layer and the second silicon nitride film layer, there is also a combination of one or more film layers such as a second oxide film layer, a backside polysilicon film layer, and a backside high-temperature oxide film layer.

[0021] Optionally, along the direction away from the substrate, the second oxide film layer, the backside polysilicon film layer, and the backside high-temperature oxide film layer are sequentially arranged between the first silicon nitride film layer and the second silicon nitride film layer.

[0022] Optionally, the third rotation is completed before the formation of the backside high-temperature oxide film layer.

[0023] Optionally, the third rotation occurs between the formation of the backside high-temperature oxide film layer and the formation of the second silicon nitride film layer.

[0024] Optionally, the fourth rotation occurs in a later period during the formation of the second silicon nitride film layer.

[0025] Optionally, the front film layer includes a pad oxide film layer, a pad nitride film layer, a thin oxide film layer, a front polysilicon film layer, a front high-temperature oxide film layer, and a sidewall nitride film layer;

[0026] The first oxide film layer is formed synchronously with the pad oxide film layer;

[0027] The first nitride film layer is formed synchronously with the pad nitride film layer;

[0028] The second oxide film layer is formed synchronously with the thin oxide film layer;

[0029] The back polysilicon film layer is formed synchronously with the front polysilicon film layer;

[0030] The back high-temperature oxide film layer is formed synchronously with the front high-temperature oxide film layer;

[0031] The second nitride film layer is formed synchronously with the sidewall nitride film layer.

[0032] Optionally, the furnace tube includes a plurality of boat feet, and the substrate is placed on the boat feet; after rotating the substrate, the contact position between the back surface of the substrate and the boat feet does not coincide with that before rotation.

[0033] Optionally, the furnace tube includes three boat feet, and the angle of each rotation is greater than 0° and not equal to 120°.

[0034] Optionally, the angle of each rotation includes 15°, 20°, and 35°.

[0035] Optionally, the angle of each rotation is greater than 0.1°.

[0036] The present invention also provides a semiconductor integrated circuit chip manufactured by the above method for manufacturing a wafer.

[0037] The beneficial effects of the present invention are as follows:

[0038] (1) In order to form a back film layer on all parts of the back surface of the substrate, the present invention adds a step of rotating the substrate in the furnace tube process. The contact position between the rotated wafer and the boat feet does not coincide with that between the wafer before rotation and the boat feet. Therefore, after rotation, when continuing to form a back film layer on the back surface of the substrate, the area of the back surface of the substrate that was blocked by the boat feet before rotation can be exposed, and the new back film layer can fill this area. After the furnace tube process is completed, all parts of the back surface of the substrate can be protected by the back film layer, and it is not easy to generate particle contamination in the subsequent process.

[0039] (2) The present invention includes at least two steps of rotating the substrate, so that the thickness of the back film layer of the substrate is uniform everywhere, and will not be too thin or too thick.

[0040] (3) The linear oxide film layer is formed by low-pressure radical oxidation (LPRO). Compared with the in-situ steam generation (ISSG) method, it can increase the process window of subsequent processes (such as wet etching, etc.), making it less likely for the substrate to be directly exposed and reducing the possibility of silicon in the substrate becoming a source of defects. Description of the Drawings

[0041] Figure 1 It is a flowchart of the manufacturing method of the wafer of the present invention.

[0042] Figures 2 - 9 It is a schematic diagram of the process of the manufacturing method of the wafer of the present invention.

[0043] In the figure, 1 - substrate, 2 - first oxide film layer, 3 - first silicon nitride film layer, 4 - back linear oxide film layer, 5 - second oxide film layer, 6 - back polysilicon film layer, 7 - back high-temperature oxide film layer, 8 - second silicon nitride film layer. Detailed Embodiments

[0044] Next, the technical solution of the present invention will be clearly and completely described in conjunction with the drawings. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative work shall fall within the protection scope of the present invention.

[0045] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is 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 orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0046] In the description of the present invention, it should be noted that unless otherwise clearly defined and limited, the terms "installed", "connected", "connected" 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 directly connected, or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0047] The preparation process of the CMOS image sensor includes:

[0048] Step 1: Provide a substrate. The substrate includes a front side and a back side opposite to the front side. Place the substrate on the boat feet of the inner boat in the furnace tube, with the back side of the substrate facing the boat feet. Form a pad oxide film layer and a pad nitride film layer on the front side of the substrate in sequence.

[0049] Step 2: Form a photoresist on the pad nitride film layer. Using this photoresist as a mask, etch the pad nitride film layer (Pad oxide), the pad oxide film layer (Pad SiN), and the substrate to form a shallow trench isolation (STI).

[0050] Step 3: Form a front side linear oxide film layer (STI Liner oxide) on the sidewalls and bottom of the shallow trench isolation, and then fill the shallow trench isolation with an insulating medium.

[0051] Step 4: Use chemical mechanical polishing (CMP) to remove the insulating medium filled outside the shallow trench isolation, and then use a wet etching process to remove the pad nitride film layer and the pad oxide film layer.

[0052] Step 5: Form a thin oxide layer (Thin oxide), a front side polysilicon film layer (Poly), a front side high temperature oxide film layer (HTO), and a sidewall nitride film layer (Spacer SiN) on the front side of the substrate in sequence.

[0053] The above Steps 1 - 5 only exemplarily show a part of the manufacturing process of the CMOS image sensor in the furnace tube. Since the back side of the substrate provided in Step 1 does not include a back seal, in order to prevent elements such as boron and phosphorus or metal ions in the substrate from falling off from the back side of the substrate and affecting the product performance, in the present invention, through the formation of each front side film layer in the furnace tube process, a back side film layer is synchronously formed on the back side of the substrate, and this back side film layer is used as the back seal of the wafer.

[0054] To solve the problem that part of the back side of the substrate is blocked by the boat feet and a back side film layer cannot be formed, resulting in part of the back side of the substrate being exposed and prone to particle contamination in subsequent processes, as Figure 1 shown, the present invention provides a method for manufacturing a wafer, including:

[0055] Step S1: Provide a substrate and send the substrate into the furnace tube.

[0056] The substrate includes a front side and a back side opposite to the front side. Place the substrate on the boat feet of the inner boat in the furnace tube, with the back side of the substrate facing the boat feet. Optionally, there are three boat feet, and the three boat feet are evenly arranged along the circumferential direction of the circle, with an interval of 120° between adjacent boat feet.

[0057] Step S2, form a front film layer on the substrate, and use the formation of the front film layer to simultaneously form a back seal including at least one layer of back film layer.

[0058] Taking steps 1 - 5 of the above - mentioned CMOS image sensor manufacturing process as an example, the front film layer at least includes a pad oxide film layer, a pad nitride film layer, a linear oxide film layer, a thin oxide film layer, a front polysilicon film layer, a front high - temperature oxide film layer, and a sidewall nitride film layer. By using the formation of the front film layer, a back film layer is formed on the back of the substrate, and the back film layer is used as the back seal of the wafer. The back film layer specifically includes: a first oxide film layer formed simultaneously with the pad oxide film layer, a first nitride film layer formed simultaneously with the pad nitride film layer, a back linear oxide film layer formed simultaneously with the front linear oxide film layer, a second oxide film layer formed simultaneously with the thin oxide film layer, a back polysilicon film layer formed simultaneously with the front polysilicon film layer, a back high - temperature oxide film layer formed simultaneously with the front high - temperature oxide film layer, and a second nitride film layer formed simultaneously with the sidewall nitride film layer.

[0059] Before wet etching, a first oxide film layer, a first nitride film layer, and a back linear oxide film layer are sequentially formed on the back of the substrate. Since the wet etching process will damage the film layer containing oxide, after the wet etching process, the back linear oxide film layer on the back of the substrate is etched, and the second oxide film layer is formed on the surface of the first nitride film layer.

[0060] The linear oxide film layer is formed by the method of low - pressure radical oxidation (LPRO). Compared with the method of in - situ steam generation (ISSG), it can increase the process window of subsequent processes (such as wet etching, etc.), make the substrate not easily directly exposed, and reduce the possibility of silicon in the substrate becoming a defect source.

[0061] Step S3, rotate the substrate so that the contact position between the substrate and the furnace tube does not coincide.

[0062] Under the shielding of the boat feet, part of the area on the back of the substrate cannot form a back film layer. If there is no film filling in this area all the time, after removing the wafer from the boat feet, this area is exposed. In subsequent processes, it will not only cause unstable back pressure, but also, since the substrate contains silicon elements, the bare silicon will cause large - particle contamination, and the particles are easy to fall onto the surface of the wafer. In the CMP process, it is also easy to cause scratches. That is to say, the area shielded by the boat feet and without a filled film layer on the back of the substrate is the main cause of defect generation.

[0063] In order to form a back film layer on all parts of the back surface of the substrate, in the furnace tube process of the present invention, a step of rotating the substrate is added. The contact position between the rotated wafer and the boat feet does not coincide with the contact position between the wafer and the boat feet before rotation. Therefore, after rotation, when continuing to form the back film layer on the back surface of the substrate, the area on the back surface of the substrate that was blocked by the boat feet before rotation can be exposed, and the new back film layer can fill this area.

[0064] Theoretically, the step of rotating the substrate can occur at various stages of the furnace tube process. It can occur before the formation of a certain back film layer, so that this back film layer can fill the area blocked by the boat feet when forming the previous back film layer; it can also occur during the formation of a certain back film layer, that is, when only a part of this back film layer is formed and the set thickness of this back film layer is not fully reached, rotate the substrate, and then form the remaining thickness of this back film layer, so that this back film layer can completely cover the back surface of the wafer.

[0065] Although the more times the substrate is rotated, the more uniform the formation of the back film layer means. However, each time the substrate is rotated, it means an increase in process steps and an extension of process time, which will affect the efficiency of the entire furnace tube process. Therefore, in actual production, the number of times of rotating the substrate is not the more the better. In order to balance the protection of the wafer and the efficiency of the furnace tube process, the step of rotating the substrate can be considered from the following aspects:

[0066] (1) Rotate the substrate before forming the second back film layer.

[0067] After forming the first back film layer, the area on the back surface of the substrate that does not contact the boat feet lacks the protection of the first back film layer. In order to fill the area not protected by the first back film layer and make all areas on the back surface of the substrate form a back film layer as soon as possible. Therefore, rotate the substrate before forming the second back film layer to make all parts of the back surface of the substrate have the protection of the back film layer at the earliest possible stage of the furnace tube process.

[0068] (2) After forming a certain back film layer, when the thickness between the boat feet and the back surface of the substrate is less than Rotate the substrate.

[0069] The thicker the back film layer, the better the protection effect on the substrate. The thickness of the back film layer at all parts of the wafer should at least reach Even if a back film layer has been formed on the back surface of the wafer, but if the thickness between the boat feet and the back surface of the substrate (that is, the thickness of the back film layer corresponding to the boat feet) is less than If the substrate is not rotated at this time and the furnace tube process is continued, the thickness of the back film layer corresponding to the boat feet will always be less than So that the back film layer at this place will always not reach the minimum thickness requirement of the back film layer. Therefore, when the thickness between the boat feet and the back surface of the substrate is less than When rotating the substrate, the contact area between the boat feet and the wafer is changed, and by forming the next back mask layer, the area with too small thickness (i.e., the part of the back mask layer corresponding to the boat feet before rotation) existing before rotation is filled, so that there is at least of the back mask layer on each part of the back of the substrate.

[0070] (3) After forming a back mask layer containing silicon element, rotate the substrate.

[0071] The back mask layer may contain silicon element. If the silicon element in the back mask layer is exposed, it is still possible to cause particle contamination. According to whether it surrounds the boat feet, the surface of the back mask layer can be divided into two parts: the first part of the surface surrounds the boat feet, and the second part of the surface does not surround the boat feet. When forming the subsequent back mask layer without rotating the substrate, only the second part of the surface can be covered, and the first part of the surface will never be covered by the subsequent back mask layer. After the process is completed, when the wafer is taken out from the boat feet, the first part of the surface of the back mask layer containing silicon element, lacking the coverage of the subsequent back mask layer, will become the source of particulate contamination. Therefore, after forming the back mask layer containing silicon element, at least one rotation should be included to make the subsequent back mask layer cover both the first part of the surface of the back mask layer containing silicon element and the second part of the surface of the back mask layer containing silicon element, reducing the exposure of the back mask layer containing silicon element.

[0072] (4) When a back mask layer containing nitrogen element has a relatively thick preset thickness, rotate the substrate during the formation of this back mask layer.

[0073] The back mask layer containing nitrogen element has stable properties and is not easily damaged by processes such as etching or grinding. Therefore, when forming a relatively thick back mask layer containing nitrogen element, the process can be divided into two steps, that is, rotate the substrate during the formation of this back mask layer. After the back mask layer containing nitrogen element is completely formed, the back of the wafer is covered with this back mask layer everywhere, playing a stable protection role for the back of the wafer.

[0074] In the furnace tube process, a back mask layer with a total thickness of several thousand angstroms will finally be formed on the back of the wafer. If the number of rotations is too small, for example, only rotate the substrate once, in the area where the back of the substrate is blocked by the boat feet for a long time, the thickness of the back mask layer between the boat feet and the back of the substrate is too thin, affecting the performance of the wafer. Therefore, in the present invention, the rotation includes at least two times.

[0075] In some embodiments, the directions of adjacent rotations are opposite, and the angles of adjacent rotations are the same or different. Optionally, the angle of the first rotation is opposite to the direction of the second rotation and the angles are the same.

[0076] In some embodiments, the directions of adjacent rotations are the same, and the angles of adjacent rotations are the same or different.

[0077] In some embodiments, the furnace tube includes three of the boat feet, and the angle of each rotation is greater than 0° and not equal to 120°.

[0078] In some embodiments, the angle of each rotation includes 15°, 20°, 35°.

[0079] In some embodiments, since the boat feet have a certain width, when the rotation angle is too small, there may be an overlap between the area blocked by the boat feet before rotation and the area blocked by the boat feet after rotation. Therefore, it is specified that the angle of each rotation is greater than 0.1° so that the contact positions of the back of the substrate with the boat feet after rotation do not overlap.

[0080] Embodiment 1

[0081] In this embodiment, the rotation includes a first rotation and a second rotation. The directions of the two rotations are opposite, and each rotation is 180°. Through the two rotations, a back seal that meets the first preset requirements is formed. Among them, the first preset requirements refer to the requirements for meeting the back seal effect of the wafer itself.

[0082] Step S1.1: Provide a substrate 1. The substrate 1 includes a front surface and a back surface opposite to the front surface. Place the substrate 1 on the boat feet of the inner boat of the furnace tube, with the back surface of the substrate 1 facing the boat feet. There are three boat feet, and the three boat feet are evenly arranged along the circumferential direction of the circle, with a 120° interval between adjacent boat feet. The position of the boat feet at this time is denoted as A.

[0083] Step S1.2, as Figure 2 shown, form a pad oxide film layer on the front surface of the substrate 1, and simultaneously form a first oxide film layer 2 on the back surface of the substrate 1 by using the formation of the pad oxide film layer. At this time, the back surface of the substrate 1 corresponding to the position A is blocked by the boat feet and no back film layer is formed, and the back surface of the substrate 1 is exposed. The thickness of the first oxide film layer 2 is

[0084] Step S1.3: Rotate the substrate 1 for the first time, rotate the substrate 1 by 180°, and the position of the boat feet after rotation is denoted as B. Since the interval between adjacent boat feet is 120°, the positions A and B do not overlap.

[0085] Step S1.4: Form a pad silicon nitride film layer on the surface of the pad oxide film layer, and simultaneously form a first silicon nitride film layer 3 on the surface of the first oxide film layer 2 on the back surface of the substrate 1 by using the formation of the pad oxide film layer. At this time, the back surface of the substrate 1 corresponding to the position A is filled with the first silicon nitride film layer 3. The back surface of the substrate 1 is covered with a back film layer everywhere.

[0086] Step S1.5, during the formation of the first silicon nitride film layer 3, rotate the substrate 1 for the second time, rotate the substrate 1 by 180°, the direction of the second rotation is opposite to that of the first rotation, and the boat foot returns to position A after rotation. In this embodiment, the first silicon nitride film layer 3 is formed in two steps. In step S1.4, position A is filled with the first silicon nitride film layer 3 and position B is not filled with the first silicon nitride film layer 3. After the second rotation, the boat foot returns to position A, so that the remaining first silicon nitride film layer 3 can continue to fill position B. Therefore, both position A and position B are filled with the first silicon nitride film layer 3 with relatively stable properties. The thickness of the first silicon nitride film layer 3 is

[0087] Embodiment 2

[0088] In this embodiment, the rotation includes a first rotation and a second rotation. The directions of the two rotations are opposite, and each rotation is 180°. Through the two rotations, a back seal that meets the first preset requirements is formed.

[0089] Steps S2.1 - S2.3 of this embodiment are exactly the same as steps S1.1 - S1.3 of Embodiment 1. At this time, the boat foot is located at position B.

[0090] Step S2.4, as Figure 3 shown, form a pad silicon nitride film layer on the surface of the pad oxide film layer, and synchronously form the first silicon nitride film layer 3 on the first oxide film layer 2 on the back of the substrate 1 by using the formation of the pad oxide film layer. At this time, the back of the substrate 1 corresponding to position A is filled with the first silicon nitride film layer 3. The thickness of the first silicon nitride film layer 3 is

[0091] Step 2.5, rotate the substrate 1 for the second time, rotate the substrate 1 by 180°, the direction of the second rotation is opposite to that of the first rotation, and the boat foot returns to position A after rotation.

[0092] Step 2.6, form a photoresist on the pad silicon nitride film layer, and use this photoresist as a mask to etch the pad silicon nitride film layer, the pad oxide film layer and the substrate 1 to form a shallow isolation trench. As Figure 4 shown, form a positive linear oxide film layer on the sidewall and bottom of the shallow isolation trench, and synchronously form a back linear oxide film layer 4 on the surface of the first silicon nitride film layer 3 on the back of the substrate 1 by using the formation of the positive linear oxide film layer. At this time, the back of the substrate 1 corresponding to position A is blocked by the boat foot and is not filled with the back linear oxide film layer 4. The thickness of the back linear oxide film layer 4 is

[0093] After step S2.4, position A is at least filled with a thickness of the first silicon nitride film layer 3, but on the back surface of the substrate 1 corresponding to position B, there is only the one formed in step S2.2 with a thickness of the first oxide film layer 2. If the thickness of the back film layer is too thin, in the subsequent wet etching process, the back film layer is easily consumed by the etching process, resulting in the exposure of the back surface of the substrate 1. Therefore, in step S2.5, the substrate 1 is rotated once again so that the back linear oxide film layer 4 in step S2.6 can fill position B again.

[0094] Embodiment 3

[0095] In this embodiment, the rotation includes the first rotation, the second rotation, and the third rotation. The directions of two adjacent rotations are opposite, and each rotation is 180°. Through three rotations, a back seal meeting the second preset requirement is formed. The second preset requirement specifically refers to: for the layer that is inevitably introduced on the back surface of the wafer during the fabrication of the required devices on the wafer and is prone to dropping pollution sources, the requirement for the back seal effect of satisfying this additionally introduced layer is the second preset requirement.

[0096] Steps S3.1 - S3.6 of this embodiment are exactly the same as steps S2.1 - S2.6 of Embodiment 2. At this time, the boat feet are located at position A.

[0097] Step S3.7, fill the shallow isolation trench with an insulating medium, remove the insulating medium filled outside the shallow isolation trench by chemical mechanical polishing (CMP), and then remove the pad silicon nitride film layer and the pad oxide film layer by a wet etching process. The back linear oxide film layer 4 is removed synchronously.

[0098] Step S3.8, as Figure 5 shown, form a thin oxide film layer on the front surface of the substrate 1, and synchronously form a second oxide film layer 5 on the surface of the first silicon nitride film layer 3 on the back surface of the substrate 1 by the formation of the thin oxide film layer. The thickness of the second oxide film layer 5 is

[0099] Step S3.9, as Figure 6 shown, form a front polysilicon film layer on the surface of the thin oxide film layer, and synchronously form a back polysilicon film layer 6 on the surface of the second oxide film layer 5 on the back surface of the substrate 1 by the formation of the front polysilicon film layer. The thickness of the back polysilicon film layer 6 is

[0100] Step S3.10, as Figure 7 shown, form a front high-temperature oxide film layer on the surface of the front polysilicon film layer, and synchronously form a back high-temperature oxide film layer 7 on the surface of the back polysilicon film layer 6 on the back surface of the substrate 1 by the formation of the front high-temperature oxide film layer. The thickness of the back high-temperature oxide film layer 7 is

[0101] Step S3.11: Rotate the substrate 1 for the third time, rotating the substrate 1 by 180°, where the direction of the third rotation is opposite to that of the second rotation, and the boat feet return to position B after rotation.

[0102] The main component of the back polysilicon film layer 6 is silicon. When forming the back polysilicon film layer 6 in step S3.9, the boat feet are at position A. If the substrate 1 is not rotated any further thereafter, after the process is completed, the first part of the surface of the back polysilicon film layer 6 (surrounding the boat feet) will not be covered by the subsequent back film layer all the time, which will become a source of particulate contamination. In this embodiment, after forming the back polysilicon film layer 6, first do not rotate the substrate 1, so that the back high-temperature oxide film layer 7 formed after the back polysilicon film layer 6 first covers the second part of the surface of the back polysilicon film layer 6 (not surrounding the boat feet), and then rotate the substrate 1, and the boat feet return to position B, so that the back film layer formed after the back high-temperature oxide film layer 7 can cover the first part of the surface of the back polysilicon film layer 6.

[0103] Embodiment 4

[0104] In this embodiment, the rotation includes the first rotation, the second rotation, the third rotation and the fourth rotation. The directions of adjacent two rotations are opposite, and each rotation is 180°. Through four rotations, a back seal meeting the third preset requirement is formed.

[0105] Steps S4.1 - S4.11 of this embodiment are exactly the same as steps S3.1 - S3.11 of Embodiment 3. At this time, the boat feet are at position B.

[0106] Step S4.12, as Figure 8 shown, form a sidewall silicon nitride film layer on the surface of the front high-temperature oxide film layer, and simultaneously form a second silicon nitride film layer 8 on the surface of the back high-temperature oxide film layer 7 on the back of the substrate 1 by using the formation of the sidewall silicon nitride film layer.

[0107] Step S4.13: When the thickness of the sidewall silicon nitride film layer reaches at least one half of the preset value, rotate the substrate 1 for the fourth time, rotating the substrate 1 by 180°, where the direction of the fourth rotation is opposite to that of the third rotation, and the boat feet return to position A after rotation. The thickness of the second silicon nitride film layer 8 formed before rotation is greater than or equal to

[0108] Step S4.14, as Figure 9 shown, continue to form the remaining sidewall silicon nitride film layer, and continue to simultaneously form the remaining second silicon nitride film layer 8 on the surface of the back high-temperature oxide film layer 7 on the back of the substrate 1. The thickness of the remaining second silicon nitride film layer 8 is less than Since there is also a high-temperature oxide film layer 7 between the back polysilicon film layer 6 and the second silicon nitride film layer 8 at position B, the high-temperature oxide film layer 7 can also play a certain back-sealing role. However, there is only the second silicon nitride film layer 8 on the back polysilicon film layer 6 at position A. In order to ensure that each position of the back polysilicon film layer 6 has a back-sealing layer with consistent performance, the second silicon nitride film layer 8 at position A on the back polysilicon film layer 6 is made thicker to facilitate ensuring the back-sealing effect.

[0109] The second silicon nitride film layer 8 contains nitrogen elements and has stable properties, and is not easily damaged by processes such as etching or grinding. The second silicon nitride film layer 8 is the last back film layer formed in the furnace tube process and is the back film layer farthest from the back of the substrate 1. Therefore, the formation of the second silicon nitride film layer 8 is carried out in two steps, and the substrate 1 is rotated during the formation of the second silicon nitride film layer 8. After the second silicon nitride film layer 8 is completely formed, the back of the wafer is covered with the second silicon nitride film layer 8 everywhere, which plays a stable protection role for the back of the wafer.

[0110] Figures 2 - 9 The various processes of the front of the substrate 1 in the furnace tube process are omitted, Figures 2 - 9 only for the schematic illustration of the back film layer of the substrate 1.

[0111] In summary, the present invention discloses a method for manufacturing a wafer and a semiconductor integrated circuit chip. The method for manufacturing a wafer includes: providing a substrate, and feeding the substrate into a furnace tube; forming a front film layer on the substrate, and using the formation of the front film layer to synchronously form a back seal including at least one back film layer; rotating the substrate so that the contact position of the wafer with the furnace tube does not coincide; the rotation includes a first rotation and a second rotation, and through at least two rotations, a back seal with a first preset requirement is formed. In order to enable back film layers to be formed everywhere on the back of the substrate, the present invention adds a step of rotating the substrate in the furnace tube process. The contact position of the rotated wafer with the boat feet does not coincide with the contact position of the wafer with the boat feet before rotation. Therefore, after rotation, when continuing to form a back film layer on the back of the substrate, the area on the back of the substrate that was blocked by the boat feet before rotation can be exposed, and the new back film layer can fill this area. After the furnace tube process is completed, the back of the substrate can be protected by back film layers everywhere, and it is not easy to generate particle contamination in subsequent processes.

[0112] Although the content of the present invention has been introduced in detail through the above preferred embodiments, it should be recognized that the above description should not be considered as a limitation of the present invention. After those skilled in the art have read the above content, various modifications and substitutions to the present invention will be obvious. Therefore, the protection scope of the present invention should be defined by the appended claims.

Claims

1. A manufacturing method of a wafer, characterized in that, comprising: providing a substrate and feeding the substrate into a furnace tube; forming a front film layer on the substrate, and synchronously forming a back seal including at least one layer of back film layer by using the formation of the front film layer; rotating the substrate so that the contact positions of the wafer and the furnace tube do not coincide; the rotation includes a first rotation and a second rotation, and through at least two rotations, a back seal meeting a first preset requirement is formed.

2. The manufacturing method of a wafer according to claim 1, characterized in that, the rotation further includes a third rotation, and through at least three rotations, a back seal meeting a second preset requirement is formed.

3. The manufacturing method of a wafer according to claim 2, characterized in that, the rotation further includes a fourth rotation, and the third rotation and the fourth rotation occur in the same layer of back film layer to form a back seal meeting a third preset requirement.

4. The manufacturing method of a wafer according to any one of claims 1-3, characterized in that, the back film layer includes a silicon nitride film layer and / or a back high-temperature oxide film layer; the rotation occurs before the formation of the silicon nitride film layer and / or the back high-temperature oxide film layer starts; and / or the rotation occurs during the formation of the silicon nitride film layer.

5. The manufacturing method of a wafer according to claim 4, characterized in that, the back film layer includes a first oxide film layer and a first silicon nitride film layer adjacent to the substrate in sequence, the first rotation occurs before the formation of the first silicon nitride film layer, and the second rotation occurs during or after the formation of the first silicon nitride film layer.

6. The manufacturing method of a wafer according to claim 5, characterized in that, the rotation occurs during the formation of the first silicon nitride film layer, and the substrate is rotated once immediately after the formation of the first silicon nitride film layer.

7. The manufacturing method of a wafer according to claim 5, characterized in that, the directions of adjacent rotations are opposite, and the angles of adjacent rotations are the same or different.

8. The manufacturing method of a wafer according to claim 7, characterized in that, the direction of the first rotation is opposite to that of the second rotation, and the angles are the same.

9. The manufacturing method of a wafer according to claim 5, characterized in that, the directions of adjacent rotations are the same, and the angles of adjacent rotations are the same or different.

10. The manufacturing method of a wafer according to claim 5, characterized in that, on the side of the first silicon nitride film layer away from the substrate, the back film layer further includes a second silicon nitride film layer adjacent to the first silicon nitride film layer, and the third rotation occurs before the formation of the second silicon nitride film layer.

11. The manufacturing method of a wafer according to claim 10, characterized in that, the fourth rotation occurs during the formation of the second silicon nitride film layer.

12. The manufacturing method of a wafer according to any one of claims 10-11, characterized in that, between the first silicon nitride film layer and the second silicon nitride film layer, there is also a combination of one or more of a second oxide film layer, a back polysilicon film layer, and a back high-temperature oxide film layer.

13. The manufacturing method of the wafer as described in claim 12, characterized in that, along the direction away from the substrate, the second oxide film layer, the back polysilicon film layer, and the back high-temperature oxide film layer are sequentially arranged between the first silicon nitride film layer and the second silicon nitride film layer.

14. The manufacturing method of the wafer as described in claim 12, characterized in that, the third rotation is completed before the formation of the back high-temperature oxide film layer.

15. The manufacturing method of the wafer as described in claim 12, characterized in that, the third rotation occurs between the formation of the back high-temperature oxide film layer and the formation of the second silicon nitride film layer.

16. The manufacturing method of the wafer as described in claim 12, characterized in that, the fourth rotation occurs and is completed at a relatively late stage during the formation of the second silicon nitride film layer.

17. The manufacturing method of the wafer as described in claim 12, characterized in that, the front film layer includes a pad oxide film layer, a pad silicon nitride film layer, a thin oxide film layer, a front polysilicon film layer, a front high-temperature oxide film layer, and a sidewall silicon nitride film layer; the first oxide film layer is formed synchronously with the pad oxide film layer; the first silicon nitride film layer is formed synchronously with the pad silicon nitride film layer; the second oxide film layer is formed synchronously with the thin oxide film layer; the back polysilicon film layer is formed synchronously with the front polysilicon film layer; the back high-temperature oxide film layer is formed synchronously with the front high-temperature oxide film layer; the second silicon nitride film layer is formed synchronously with the sidewall silicon nitride film layer.

18. The manufacturing method of the wafer as described in claim 1, characterized in that, the furnace tube includes a plurality of boat feet, and the substrate is placed on the boat feet; after rotating the substrate, the contact position between the back surface of the substrate and the boat feet does not coincide with that before rotation.

19. The manufacturing method of the wafer as described in claim 18, characterized in that, the furnace tube includes three boat feet, and the angle of each rotation is greater than 0° and not equal to 120°.

20. The manufacturing method of the wafer as described in claim 19, characterized in that, the angle of each rotation includes 15°, 20°, and 35°.

21. The manufacturing method of the wafer as described in claim 19, characterized in that, the angle of each rotation is greater than 0.1°.

22. A semiconductor integrated circuit chip, characterized in that, it is obtained by the manufacturing method of the wafer as described in any one of claims 1 - 21.

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