Vertical boat
The vertical boat design with inclined support columns and controlled CVD film thickness addresses uneven deposition issues, enhancing wafer quality and durability by minimizing particle generation and film wear.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- COORSTEK GK
- Filing Date
- 2024-12-13
- Publication Date
- 2026-06-25
AI Technical Summary
In vertical semiconductor heat treatment furnaces, the uneven deposition of CVD films in grooves leads to particle generation and mechanical wear, affecting the quality and durability of semiconductor wafers due to friction and film peeling.
A vertical boat design with support columns featuring a 30 mm or more horizontal length from the intersection to the tip, an inclined upper surface, and a 30-40% thinner CVD film at the intersection compared to the tip, ensuring minimal film wear and improved flatness.
The design suppresses particle generation and enhances wafer quality by maintaining CVD film integrity and flatness, reducing friction and mechanical damage during wafer insertion.
Smart Images
Figure 2026103914000001_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a vertical boat for a semiconductor heat treatment furnace.
Background Art
[0002] Conventionally, heat treatment processes such as LP-CVD (low-pressure chemical vapor deposition) and annealing of semiconductors have been performed using a vertical semiconductor heat treatment furnace (see Patent Documents 1 and 2 below).
[0003] In recent years, with the miniaturization of semiconductors, minute crystal defects generated in a semiconductor substrate have caused deterioration of the electrical characteristics of each element such as transistors and capacitors formed on the semiconductor substrate, resulting in a decrease in the yield in the manufacturing process of semiconductor devices. Therefore, it is necessary to reduce crystal defects on the surface of a semiconductor substrate by subjecting the semiconductor substrate to a high-temperature process of 1000°C or higher.
[0004] Therefore, by using a SiC material having excellent heat resistance as a member in a semiconductor heat treatment furnace, an improvement in productivity in the manufacturing process of semiconductor devices has been expected. Furthermore, by applying a highly pure SiC film to a Si-SiC substrate, the material is made ultra-highly pure, contamination of the semiconductor substrate is reduced, and the thermal expansion coefficient is approximated to that of deposition films such as Si and SiN generated in the manufacturing process of semiconductor devices, thereby reducing particles due to peeling of the deposition film.
Prior Art Documents
Patent Documents
[0005]
Patent Document 1
Patent Document 2
Summary of the Invention
Problems to be Solved by the Invention
[0006] For example, in the process of forming a CVD film of SiC or the like on the surface of a vertical SiC boat for semiconductor heat treatment furnaces that has grooves longer than 30 mm, the raw material gas enters from the front (outside) of the groove due to the shape of the product. As a result, the amount of coating on the deeper side of the groove is less than the amount of coating on the leading side of the groove, and for example, in a vertical boat with grooves longer than 90 mm, it is about 30-40% less.
[0007] Conventionally, when forming grooves in vertical boats, a processing tool was inserted horizontally to ensure high groove flatness, for example, a groove flatness of 0.02 mm or less. However, when a CVD film is deposited as described above, the difference in the amount of CVD film between the inner and outer ends of the groove results in the outer end being higher than the inner end, leading to a decrease in flatness.
[0008] When a vertical boat with this type of film deposition is used in an on-site process, the back surface of the semiconductor wafer is likely to come into contact with the tip of the groove when inserting the semiconductor wafer into the groove of the vertical boat, and particles are likely to be generated from the back surface of the vertical boat due to friction.
[0009] Furthermore, at the tips of the grooves in the vertical boat, the CVD film attached to the surface is easily worn away by mechanical damage, reducing the vertical boat's resistance to heat and chemicals. Repeated thermal shocks and chemical damage make the CVD film more susceptible to peeling. If the CVD film peels off, it can become a source of particle generation originating from the vertical boat in the on-site process, or a source of purity abnormalities in semiconductor wafers after on-site processing.
[0010] This invention was made to solve the above-mentioned problems and aims to suppress particles and improve the quality of semiconductor wafers. [Means for solving the problem]
[0011] The vertical boat of disclosure is, A vertical boat having a top plate, a bottom plate, and support columns, The support column has a column portion, one end of which is fixed to the top plate and the other end of which is fixed to the bottom plate, and a support portion that protrudes from the side of the column portion and horizontally supports the semiconductor wafer. The length from the point where the support portion intersects the column portion to the tip of the support portion is 30 mm or more. The upper surface of the support portion is inclined downward from the point of intersection to the tip. It is. [Effects of the Invention]
[0012] According to the present invention, it is possible to suppress particles and improve the quality of semiconductor wafers. [Brief explanation of the drawing]
[0013] [Figure 1] This is a cross-sectional view showing a semiconductor processing apparatus 1, which is an example of a semiconductor processing apparatus to which the vertical boat according to this embodiment can be applied. [Figure 2] This figure shows an example of the overall configuration of wafer boat 4. [Figure 3] This figure shows an example of a state in which a semiconductor wafer W is placed on a wafer boat 4. [Figure 4] This figure shows an example of the structure of support column 43A. [Figure 5] This figure shows a magnified view of a portion of the support column 43A shown in Figure 4. [Figure 6] This graph shows an example of groove flatness at each groove position on the wafer boat 4. [Modes for carrying out the invention]
[0014] Hereinafter, an example of a vertical boat for a semiconductor device according to this embodiment will be described with reference to the drawings.
[0015] <Configuration of semiconductor processing equipment> Figure 1 is a cross-sectional view showing a semiconductor processing apparatus 1, which is an example of a semiconductor processing apparatus to which the vertical boat according to this embodiment can be applied.
[0016] The vertical semiconductor processing apparatus 1 shown in FIG. 1 includes a core tube 2 having an overall cylindrical shape. This core tube 2 has an opening 3 at the lower part, and a large number of semiconductor wafers W mounted on a wafer boat 4 are taken in and out through this opening 3. The "vertical boat" of the present invention can be applied to the wafer boat 4 as an example. In FIG. 1, the structure of the wafer boat 4 is shown in a simplified manner.
[0017] The core tube 2 is made of quartz glass, and a processing space 5 is formed inside it. In the processing space 5, for example, two gas introduction tubes 6 with different lengths are provided, and a predetermined gas (for example, silane gas) can be introduced into the processing space 5.
[0018] The gas introduction tube 6 is a tube having a gas inlet 6a and a gas outlet 6b, and is formed in an L shape in the example shown in FIG. 1. That is, the gas introduction tube 6 is composed of a horizontal portion 6h arranged horizontally in the core tube 2, a bent portion 6c bent at about 90 degrees, and a vertical portion 6v arranged vertically in the core tube 2.
[0019] Also, in the semiconductor processing apparatus 1, an elevating device 10 for opening and closing the opening 3 is provided near the bottom of the core tube 2, and a boat table 11 for supporting the wafer boat 4 is placed thereon. Around the core tube 2, a heater 12 for heating the core tube 2 is provided. An exhaust port 13 for the processing gas is provided at the top of the core tube 2.
[0020] <Heat treatment of semiconductor wafers in the semiconductor processing apparatus 1> In the semiconductor processing apparatus 1 configured as described above, first, the wafer boat 4 on which a large number of semiconductor wafers W are placed is placed on the boat table 11 placed on the elevating device 10 and stored in the core tube 2 heated by the heater 12.
[0021] Then, the temperature inside the reactor core tube 2 is further increased, and for example, a process gas doped with heated boron is introduced into the reactor core tube 2 from the gas introduction tube 6. The introduced process gas deposits a silicon film onto the semiconductor wafer W, and then the process gas is exhausted from the exhaust port 13.
[0022] <Overall configuration of wafer boat 4> Figure 2 shows an example of the overall configuration of the wafer boat 4. Figure 2 shows the top surface (upper part of Figure 2) and side surface (lower part of Figure 2) of the wafer boat 4. As shown in Figure 2, the wafer boat 4 has a top plate 41, a bottom plate 42, and support columns 43A to 43C (multiple support columns).
[0023] The top plate 41 and the bottom plate 42 have a roughly disc shape and are positioned opposite each other with a gap between them. In this example, the top plate 41 and the bottom plate 42 have a roughly disc shape with the same diameter and their central axes coincide. The central axis of the top plate 41 and the bottom plate 42 is defined as the central axis 40.
[0024] The support columns 43A to 43C have a roughly cylindrical shape and extend parallel to the central axis 40. Each of the support columns 43A to 43C has one end (upper end) fixed to the top plate 41 and the other end (lower end) fixed to the bottom plate 42. In this example, the support columns 43A to 43C are arranged at equal intervals at three locations on concentric circles centered on the central axis 40, when viewed in the direction of the central axis 40.
[0025] The wafer boat 4 is placed on the boat table 11 (see Figure 1) with one side of the bottom plate 42 (the side opposite to the top plate 41) facing downwards (in the direction of gravity). In this case, the top plate 41 and bottom plate 42 have a roughly circular surface that is horizontal, and the support columns 43A to 43C are vertical.
[0026] Each of the support columns 43A to 43C has multiple grooves D. For example, the multiple grooves D of support column 43A are arranged in a direction parallel to (perpendicular to) the central axis 40 and are notches that open toward the inside of the wafer boat 4 (towards the central axis 40). Similarly, the multiple grooves D of support columns 43B and 43C are also arranged in a direction parallel to (perpendicular to) the central axis 40 and are notches that open toward the inside of the wafer boat 4 (towards the central axis 40).
[0027] Each of the support columns 43A to 43C has the same number of grooves D. In this example, each of the support columns 43A to 43C has 25 grooves D. The Nth groove D from the bottom (N=1 to 25) of each of the support columns 43A to 43C are at the same height and form support sections that horizontally support one semiconductor wafer at three points. Therefore, in this example, the support columns 43A to 43C can support a maximum of 25 semiconductor wafers.
[0028] <Semiconductor wafer placed on wafer boat 4> Figure 3 shows an example of a semiconductor wafer placed on a wafer boat 4. As shown in Figure 3, the semiconductor wafer W is placed horizontally by the support portion formed by the grooves D of the support columns 43A to 43C of the wafer boat 4. In this example, 25 semiconductor wafers W are placed, each supported at three points by the support columns 43A to 43C.
[0029] <Structure of support column 43A> Figure 4 shows an example of the structure of support column 43A. The structure of support column 43A will be described below, but the structures of support columns 43B and 43C are similar to that of support column 43A. As shown in Figure 4, support column 43A has a column portion 43a and a support portion 43b.
[0030] The column portion 43a is a part that connects the top plate 41 and the bottom plate 42, with one end (upper end) fixed to the top plate 41 and the other end (lower end) fixed to the bottom plate 42. The support portion 43b is a part formed by a groove D provided in the support column 43A, and protrudes from the side of the column portion 43a (the side facing the central axis 40) toward the inside of the wafer boat 4 (the side facing the central axis 40).
[0031] Figure 5 is an enlarged view of a portion of the support column 43A shown in Figure 4. Intersection 51 is the point where the support portion 43b intersects with the column portion 43a, that is, the base end of the support portion 43b protruding from the column portion 43a. Tip 52 is the tip of the support portion 43b, that is, the end of the support portion 43b protruding from the column portion 43a that is opposite to the base end (intersection 51).
[0032] W1 is the horizontal length from intersection 51 to tip 52. W1 is at least 30 mm long (for example, at least 90 mm). For example, W1 is approximately 140 mm.
[0033] As shown in Figure 5, a CVD film 43d is formed on the upper surface 43c of the support portion 43b. The CVD film 43d is, for example, a SiC (silicon carbide) film. Note that the CVD film 43d is not limited to a SiC film, but may be a film other than SiC. Furthermore, the CVD film 43d is not limited to the upper surface 43c of the support portion 43b, but may be formed on the entire surface of the wafer boat 4.
[0034] The amount (thickness) of the CVD film 43d at intersection 51 is, for example, 30% to 40% less than the amount (thickness) of the CVD film 43d at tip 52. This is because, for example, in the process of forming the CVD film 43d on the surface of the wafer boat 4, the raw material gas enters from the side (outside) of tip 52 due to the product shape, so the amount of film increases closer to tip 52.
[0035] At the tip 52 of the wafer boat 4, the CVD film 43d attached to the surface is susceptible to wear due to mechanical damage. However, because the amount of CVD film 43d at the tip 52 is greater than the amount of CVD film 43d at the intersection 51, the CVD film 43d is less likely to wear down, and peeling of the CVD film 43d can be suppressed. As a result, the durability of the wafer boat 4 is improved.
[0036] Furthermore, as shown in Figure 5, the upper surface 43c of the support portion 43b is inclined downward from the intersection 51 to the tip 52. The lower surface of the support portion 43b is approximately horizontal. In other words, the support portion 43b is formed such that its thickness decreases from the intersection 51 to the tip 52. By forming the support portion 43b in this shape and forming the CVD film 43d on the upper surface 43c, even if the thickness of the CVD film 43d increases from the intersection 51 to the tip 52, the upper surface of the CVD film 43d can be made approximately parallel to the lower surface of the support portion 43b, i.e., nearly horizontal.
[0037] Thus, in a wafer boat 4 where the horizontal length W1 from the intersection 51 to the tip 52 is 30 mm or more (for example, 90 mm or more), by forming the support portion 43b such that the upper surface 43c of the support portion 43b slopes downward from the intersection 51 to the tip 52, even if the thickness of the CVD film 43d increases towards the tip 52, the flatness of the upper surface of the CVD film 43d can be increased, for example, the flatness can be reduced to 0.02 mm or less.
[0038] Therefore, the upper surface of the CVD film 43d becomes nearly horizontal, and when the semiconductor wafer W is inserted horizontally into the wafer boat 4, the upper surface 43c of the support portion 43b and the back surface of the semiconductor wafer W are less likely to rub against each other, thereby suppressing the generation of particles.
[0039] The flatness of the upper surface of the CVD film 43d is, for example, the difference between the maximum and minimum heights of multiple locations (e.g., three or more locations) on the upper surface of the CVD film 43d.
[0040] It is desirable that the thickness H1 (vertical length) of the intersection 51 in the support portion 43b be 0.02% to 0.04% higher than the thickness H2 (vertical length) of the tip 52 in the support portion 43b. That is, it is desirable that the following equation (1) is satisfied.
[0041] H2 × 1.0002 ≤ H1 ≤ H2 × 1.0004 …(1)
[0042] For example, if H2 × 1.0002 > H1, when the semiconductor wafer W is placed on the support portion 43b, friction between the back surface (bottom surface) of the semiconductor wafer W and the tip 52 of the support portion 43b makes it easier for particles to be generated from the back surface of the semiconductor wafer W.
[0043] Furthermore, if H1 > H2 × 1.0004, even after the deposition of the CVD film 43d, the combined height (thickness) of the support portion 43b and the CVD film 43d will be higher at the intersection 51 than at the tip 52, resulting in the semiconductor wafer W being concentratedly supported at its edge. This can lead to problems such as the semiconductor wafer W warping after processing, resulting in a deterioration of its flatness, or the occurrence of slip defects within the semiconductor wafer W.
[0044] In contrast, these problems can be suppressed by satisfying equation (1) above.
[0045] <Groove flatness at each groove position of wafer boat 4> Figure 6 is a graph showing an example of groove flatness at each groove position of the wafer boat 4. In Figure 6, the horizontal axis represents the groove position of the wafer boat 4, i.e., the height position of groove D shown in Figures 2 and 3. For example, in Figure 6, higher groove positions are indicated as you move to the right. Also, in Figure 6, the vertical axis represents the flatness of groove D, i.e., the flatness of the upper surface 43c of the support portion 43b.
[0046] The example in Figure 6 shows the results of measuring the flatness of grooves D every 10 grooves from the 1st to the 120th groove using a three-dimensional measuring machine. The number of grooves D on the wafer boat 4 (maximum number of semiconductor wafers W that can be placed) is 120, and CVD processing is performed in the semiconductor processing apparatus 1 at an in-furnace processing temperature of 1100-1150°C. Groove flatness values 60, 61, ... represent the flatness of grooves D at the 1st, 10th, 20th, 30th, ..., 120th grooves. The maximum value of groove flatness values 60, 61, ... was 0.017 mm, which is less than or equal to 0.02 mm.
[0047] <Modified versions of support posts 43A-43C> Although the description has shown a wafer boat 4 having three support columns (columns 43A to 43C) as multiple support columns, the number of support columns on the wafer boat 4 may be two or four or more. Furthermore, the shape of each of the support columns 43A to 43C is not limited to a roughly cylindrical shape, but can be a roughly rectangular prism shape, a roughly triangular prism shape, or various other shapes.
[0048] <Modified example of gas introduction pipe 6> The gas inlet pipe 6 is not limited to the L-shape shown in Figure 1; it may also be straight. Furthermore, the gas inlet pipe 6 is not limited to the L-shape or straight shape; for example, it may have a shape that is bent at multiple points. The shape of the gas inlet pipe 6 to be used is determined according to the structure of the semiconductor processing apparatus (e.g., semiconductor processing apparatus 1) to which the gas inlet pipe 6 is applied.
[0049] This specification contains at least the following:
[0050] (1) A vertical boat having a top plate, a bottom plate, and support columns, The above-mentioned support column has a column portion, one end of which is fixed to the top plate and the other end of which is fixed to the bottom plate, and a support portion that protrudes from the side of the column portion and horizontally supports the semiconductor wafer. The length from the point where the support portion intersects with the column portion to the tip of the support portion is 30 mm or more. The upper surface of the support portion is sloped downward from the point of intersection to the tip. Vertical boat.
[0051] (2) (1) The vertical boat described above, The thickness of the support portion is such that the point where it intersects with the support column is 0.02% to 0.04% higher than the tip. Vertical boat.
[0052] (3) (1) or (2) a vertical boat, A CVD film is formed on the above support portion. Vertical boat.
[0053] (4) (3) The vertical boat described above, The amount of the CVD film at the point where it intersects with the support column is 30% to 40% less than the amount of the CVD film at the tip. Vertical boat.
[0054] (5) (3) or (4) a vertical boat, The flatness of the above CVD film is 0.02 mm or less. Vertical boat. [Explanation of Symbols]
[0055] 1. Semiconductor processing unit 2 core tubes 3 aperture 4 wafer boats 5 Processing space 6. Gas inlet pipe 6b Gas outlet 6c Bend part 6h horizontal section 6v vertical part 10 Lifting device 11 Boat Table 12 Heaters 13 Exhaust vent 40 center axis 41 Top plate 42 Bottom plate 43A~43C Post 43a Pillar 43b Support part 43c top surface 43d CVD membrane 51 intersection 52 Tip 60,61,… Groove flatness
Claims
1. A vertical boat having a top plate, a bottom plate, and support columns, The support column has a column portion, one end of which is fixed to the top plate and the other end of which is fixed to the bottom plate, and a support portion that protrudes from the side of the column portion and horizontally supports the semiconductor wafer. The length from the point where the support portion intersects the column portion to the tip of the support portion is 30 mm or more. The upper surface of the support portion is inclined downward from the point of intersection to the tip. Vertical boat.
2. A vertical boat according to claim 1, The thickness of the support portion is such that the point where it intersects with the support column is 0.02% to 0.04% higher than the tip. Vertical boat.
3. A vertical boat according to claim 1, A CVD film is formed on the support portion. Vertical boat.
4. A vertical boat according to claim 3, The amount of the CVD film at the point where it intersects with the support column is 30% to 40% less than the amount of the CVD film at the tip. Vertical boat.
5. A vertical boat according to claim 3 or 4, The flatness of the CVD film is 0.02 mm or less. Vertical boat.