Base and device for epitaxial growth of wafer
By designing a base with a specific sector-shaped structure, the problem of uneven nano-quality in wafer epitaxial growth is solved, and the uniformity of wafer thickness and nano-quality improvement is achieved.
Patent Information
- Application Number
- CN202411721848.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-28
- Publication Date
- 2025-02-28
AI Technical Summary
Existing wafer epitaxial growth bases lead to uneven wafer nanoquality, especially at the edges and centers of the wafer, where there are significant differences in thickness and nanomass.
A base is designed, and its bearing structure consists of N first sectors and N second sectors, the first sector is centered on the crystal direction of the wafer, and the second sector is centered on the crystal direction of the <110>. The thickness of the edge region of the first sector is greater than that of the internal region, and the thickness of the second sector is uniform to control the temperature difference between the base and the wafer and adjust the growth rate and thickness of the wafer.
Through this design, a more uniform wafer thickness is achieved, nano quality and yield are improved, the growth rate of wafer edges is reduced, and the uniformity of the overall wafer thickness is ensured.
Smart Images
Figure CN119530959A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of semiconductor technology, and in particular to a base and a device for wafer epitaxial growth. Background Art
[0002] The epitaxial growth process of wafers is an important process in the semiconductor chip manufacturing process. This process refers to growing a silicon single crystal layer with controllable resistivity and thickness, no Crystal Originated Particles (COP) defects and no oxygen precipitation, i.e., an epitaxial layer, on a polished wafer under certain conditions.
[0003] During the epitaxial growth of wafers, due to the different crystal growth rates between different crystal orientations, taking the wafer with (100) crystal plane as an example, <110> The growth rate of the epitaxial layer in the region where the crystal orientation group is located will be higher than <100> The area where the crystal orientation family is located causes the thickness of the epitaxial layer in different crystal orientations of the wafer to be different. This thickness difference is more obvious in the area closer to the edge of the wafer, that is, the growth rate of the epitaxial layer of the wafer in the area close to the edge of the wafer is faster.
[0004] Moreover, during the epitaxial growth of the wafer, the temperature difference between the susceptor and the wafer in a high temperature environment has an important impact on the thickness of the wafer, thereby affecting the nanometer quality of the wafer. Also, as the growth rate of the wafer in different crystal directions is different, the impact of the temperature difference on the thickness of the wafer is also different. For example, <100> In the crystal direction, the wafer growth rate is slow and is less affected by temperature differences, but <110> In the crystal direction, the wafer growth rate is fast and is greatly affected by temperature differences, which seriously affects the Nano quality of the wafer. The schematic diagram of the Nano Map of the wafer grown on the existing base is as follows: Figure 1 As shown, Figure 1 In the figure, different colors correspond to different wafer thicknesses (or Nano masses). The thickness value corresponding to red is greater than the thickness value corresponding to yellow, and the thickness value corresponding to yellow is greater than the thickness value corresponding to green. Figure 1 It can be seen that the thickness (or nano-mass) of the edge and center parts of the wafer is very uneven. Summary of the invention
[0005] The embodiment of the present invention provides a base and a device for wafer epitaxial growth, so as to solve the problem of poor nano quality of existing epitaxial wafers.
[0006] To solve the above technical problems, the embodiments of the present invention provide the following technical solutions:
[0007] An embodiment of the present invention provides a susceptor for wafer epitaxial growth, comprising:
[0008] A disc-shaped carrying structure for carrying wafers;
[0009] The disk-shaped bearing structure includes N first sector areas and N second sector areas, wherein the first sector areas are shaped like the wafer. <110> The radial direction corresponding to the crystal direction is the central axis, and the second sector area is centered on the radial direction of the wafer. <100> The radial direction corresponding to the crystal orientation is the central axis, where N is a positive integer;
[0010] The thickness of the edge region of each of the first sector-shaped areas is greater than the thickness of the inner region except the edge region;
[0011] The thickness of each of the second sector-shaped areas is uniform.
[0012] In some embodiments, the thickness of the edge region of the first sector area gradually decreases from the edge of the first sector area to the center of the first sector area.
[0013] The minimum thickness of the edge region of the first sector-shaped area is greater than the thickness of the inner region of the first sector-shaped area.
[0014] In some embodiments, the edge region of the first sector-shaped area is a region 3 mm to 10 mm away from the edge of the first sector-shaped area.
[0015] In some embodiments, the angle between the upper surface of the edge region of the first sector and the horizontal plane is in the range of 0.1°-0.5°.
[0016] In some embodiments, the thickness of the inner region of the first sector-shaped region is equal to the thickness of the second sector-shaped region.
[0017] In some embodiments, the sizes of the N first sectors are equal;
[0018] The sizes of the N second sectors are equal.
[0019] In some embodiments, the size of one of the first sector-shaped areas is equal to the size of one of the second sector-shaped areas.
[0020] In some embodiments, N first sector-shaped areas and N second sector-shaped areas are arranged alternately.
[0021] An embodiment of the present invention further provides a device for wafer epitaxial growth, comprising:
[0022] A susceptor for wafer epitaxial growth as described above;
[0023] A reaction chamber is used to accommodate the susceptor, wherein the susceptor divides the reaction chamber into an upper reaction chamber and a lower reaction chamber, and the wafer is placed in the upper reaction chamber.
[0024] The embodiments of the present invention have the following beneficial effects:
[0025] The base for wafer epitaxial growth provided by the embodiment of the present invention is divided into N first sector areas and N second sector areas by a disc-shaped supporting structure supporting the wafer, wherein the first sector area is based on the wafer <110> In the radial direction corresponding to the crystal direction, the second sector area is <100> The radial direction corresponding to the crystal direction is the central axis. During the epitaxial growth of the wafer, the temperature difference between the base and the wafer in the growth environment will affect the nanometer (Namo) quality of the wafer, and the wafer <100> The growth rate in the crystal direction is slow and is less affected by temperature differences. The thickness of the second sector area is set to be uniform so that the wafer <100> The thickness in the crystal direction is relatively uniform. Considering the <110> The growth rate in the crystal direction is fast and is greatly affected by temperature differences, and its growth rate at the edge of the wafer is even faster. Therefore, the thickness of the edge area of the first fan-shaped area is designed to be greater than the thickness of the internal area except the edge area, so as to control the temperature difference between the edge area and the center area of the base and the wafer to be different, and then interact with the different thickness values generated by the different growth rates of the wafer, so that the overall thickness of the wafer is more uniform, thereby improving the Nano quality of the wafer. BRIEF DESCRIPTION OF THE DRAWINGS
[0026] Figure 1 A schematic diagram showing a nano map of a wafer grown on a conventional base provided by the present invention;
[0027] Figure 2 A schematic diagram showing the crystal orientation of a wafer provided by an embodiment of the present invention;
[0028] Figure 3 A schematic diagram showing the structure of a base for wafer epitaxial growth provided by an embodiment of the present invention;
[0029] Figure 4 A schematic diagram showing the structure of an apparatus for wafer epitaxial growth provided by an embodiment of the present invention.
[0030] Description of reference numerals:
[0031] 1-wafer; 2-disc-shaped bearing structure; 21-first sector; 22-second sector; 3-base; 4-upper quartz bell; 5-lower quartz bell; 6-installation component; 7-base support rod; 8-heating bulb. DETAILED DESCRIPTION
[0032] In order to make the technical problems, technical solutions and advantages to be solved by the embodiments of the present invention more clear, a detailed description will be given below with reference to the accompanying drawings and specific embodiments.
[0033] In order to make the purpose, technical solution and advantages of the embodiment of the present invention clearer, the technical solution of the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings of the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the described embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present invention.
[0034] It should be noted that Figure 2 The crystal orientation of a wafer is shown by taking a wafer with a (100) crystal plane as an example. Figure 2 As shown, if the three o'clock direction of the wafer is the radial direction of 0° / 360° and is the <110> If the crystal direction is 0° / 360°, the radial directions of 90°, 180° and 270° clockwise relative to the radial direction of 0° / 360° are also the radial directions of the wafer. <110> The radial directions of 45°, 135°, 225° and 315°, which are rotated clockwise relative to the radial direction of 0° / 360°, are the crystal directions of the wafer. <100> That is to say, for this wafer, 4 <110> The crystal orientation corresponds to the four radial directions distributed at 90° intervals along the circumference of the wafer. <100> The crystal orientation also corresponds to the four radial directions distributed at 90° intervals along the circumference of the wafer, and the adjacent <110> Crystal orientation and <100> The crystal directions are spaced 45° apart along the circumference of the wafer.
[0035] In order to solve the problem of poor nano quality of existing epitaxial wafers, an embodiment of the present invention provides a base and a device for wafer epitaxial growth.
[0036] like Figure 3 As shown, an embodiment of the present invention provides a susceptor for wafer epitaxial growth, comprising:
[0037] A disc-shaped supporting structure 2 for supporting the wafer 1 .
[0038] in, Figure 3 The left side of FIG. 1 shows a schematic diagram of a wafer 1 carried on a disc-shaped carrying structure 2 .
[0039] The disk-shaped supporting structure 2 includes N first sector areas 21 and N second sector areas 22. The first sector areas 21 are shaped like the wafer. <110> The radial direction corresponding to the crystal direction is the central axis, and the second sector area 22 is centered on the radial direction of the wafer. <100> The radial direction corresponding to the crystal orientation is the central axis, where N is a positive integer;
[0040] That is, the first sector area 21 carries the wafer. <100> The part of the wafer corresponding to the crystal direction is supported by the second sector area 22. <100> Part of the wafer corresponding to the crystal orientation.
[0041] Taking the wafer with (100) crystal plane as an example, the <110> There are 4 crystal directions. <110> The number of crystal directions is 4. Therefore, in this embodiment, N is 4, that is, one first sector corresponds to one wafer. <110> Crystal direction, a second sector corresponds to a wafer <100> Crystal direction.
[0042] The thickness of the edge region of each of the first sector regions 21 is greater than the thickness of the inner region except the edge region. Figure 3 as shown in the right part of .
[0043] In all embodiments of the present invention, thickness may also be understood as a thickness value, that is, a numerical value used to indicate thickness.
[0044] During the epitaxial growth of the wafer, the high temperature environment causes a temperature difference between the base and the wafer, which will affect the nanometer (Namo) quality of the wafer. <110> Due to the fast growth rate in the crystal direction, the influence of temperature difference and the sensitivity to temperature fluctuation, the thickness of the edge area of the first sector area 21 is designed to be greater than the thickness of the internal area except the edge area, so as to control the temperature difference between the edge area and the center area of the base and the wafer respectively, and then interact with the different thickness values produced by the different growth rates of the wafer. By controlling the temperature difference, the growth rate of the wafer edge is reduced, the overall thickness of the wafer is made more uniform, the nano quality of the wafer is improved, and the yield rate is improved.
[0045] The thickness in the edge region of the first sector-shaped region 21 may be variable or constant, and the thickness in the inner region of the first sector-shaped region 21 may be variable or constant.
[0046] When the thickness changes in the edge area of the first sector area 21, the thickness should gradually decrease from the edge to the center. When the thickness changes in the internal area of the first sector area 21, the thickness should gradually decrease from the edge to the center. It is only necessary to ensure that the minimum thickness in the edge area of the first sector area 21 is greater than the maximum thickness in the internal area of the first sector area 21, so as to control the temperature difference between the edge area and the center area of the base and the wafer respectively, and then interact with the different thickness values generated by the different growth rates of the wafer. By controlling the temperature difference, the growth rate of the wafer edge is reduced, the overall thickness of the wafer is made more uniform, the Nano quality of the wafer is improved, and the yield rate is improved.
[0047] The thickness of each of the second sector areas 22 is uniform. Figure 3 as shown in the right part of .
[0048] Consider the wafer <100> The growth rate in the crystal direction is slow, the influence of temperature difference is small, and the temperature fluctuation is relatively insensitive. The thickness of the second sector area is set to be uniform, so that the wafer <100> The thickness in the crystal direction is relatively uniform.
[0049] It should be noted that the edge area of the first sector area 21 is the area 3mm to 10mm away from the edge of the first sector area 21, that is, the area 3mm to 10mm away from the edge in the first sector area 21 is defined as the edge area of the first sector area 21, and the area outside is defined as the inner area of the first sector area 21 (or called the central area of the first sector area 21).
[0050] In another optional embodiment, the thickness within the second sector area 22 may be variable. When the thickness within the second sector area 22 varies, the thickness gradually decreases from the edge of the second sector area 22 toward the center (or center of the circle) of the second sector area 22 .
[0051] It should also be noted that due to the wafer <100> The growth rate in the crystal direction is slow. <110> The growth rate in the crystal direction is fast. Therefore, in order to ensure the uniformity of the thickness of the wafer, when the thickness of the edge area of the first sector area 21 is changing or unchanged, when the thickness of the internal area of the first sector area 21 is changing or unchanged, and when the thickness of the second sector area 22 is changing or unchanged, it is only necessary to ensure that the minimum thickness of the edge area of the first sector area 21 is greater than the maximum thickness of the internal area of the first sector area 21, and to ensure that the minimum thickness of the edge area of the first sector area 21 is greater than the maximum thickness of the second sector area 22. That is, the temperature difference between the edge area and the central area of the base and the wafer can be controlled to be different, and then interact with the different thickness values generated by the different growth rates of the wafer. By controlling the temperature difference, the growth rate of the edge of the wafer is reduced, so that the overall thickness of the wafer is more uniform, the Nano quality of the wafer is improved, and the yield rate is improved. The thickness difference can be set according to needs.
[0052] In the design method provided in the embodiment of the present invention, Figure 3 As shown, the edge area of the first sector area 21 contacts the edge of the wafer 1, and the entire wafer 1 is supported by the edge area of the first sector area 21. The inner area of the first sector area 21 and the wafer 1 are hollow (non-contact), and the second sector area 22 and the wafer 1 are hollow (non-contact).
[0053] In some embodiments, the radius of the disk-shaped supporting structure 2 is greater than the radius of the wafer 1, or it can be understood that the radius of the first sector area 21 and the radius of the second sector area 22 are greater than the radius of the wafer 1, that is, the orthographic projection of the wafer on the disk-shaped supporting structure 2 does not cover the edge of the disk-shaped supporting structure 2. In this way, the wafer 1 can be placed thereon and stable support for the wafer 1 can be ensured.
[0054] The difference between the radius of the disk-shaped supporting structure 2 and the radius of the wafer 1 can be set according to the size of the wafer 1 and the size of the disk-shaped supporting structure 2 .
[0055] In some embodiments, the thickness of the edge region of the first sector-shaped area 21 gradually decreases from the edge of the first sector-shaped area 21 to the center (or center of the circle) of the first sector-shaped area 21 .
[0056] Since the wafer <110> In the crystal direction, the growth rate of the wafer gradually increases. Therefore, the thickness value of the edge area of the wafer is designed to gradually decrease, that is, the edge area of the first fan-shaped area 21 is designed to be a slope in the vertical direction. The temperature difference between the base and the wafer can be better controlled, and then interact with the different thickness values generated by the different growth rates of the wafer. By controlling the temperature difference, the growth rate of the edge of the wafer is reduced, and the overall thickness of the wafer is made more uniform, thereby improving the nano quality of the wafer and the yield rate.
[0057] In some embodiments, the minimum thickness of the edge region of the first sector-shaped area 21 is greater than the thickness of the inner region of the first sector-shaped area 21 .
[0058] Considering the wafer <110> In the crystal direction, the growth rate of the wafer will suddenly change. The minimum thickness of the edge area of the first sector area 21 is designed to be greater than the thickness of the internal area of the first sector area 21, that is, the junction between the internal area of the first sector area 21 and the edge area of the first sector area 21 is stepped, thereby reducing the influence of the sudden change in the growth rate of the wafer on the thickness value and obtaining a wafer with better flatness.
[0059] In some embodiments, the thickness of the inner region of the first sector-shaped region 21 is equal to the thickness of the second sector-shaped region 22 .
[0060] Due to the wafer <100> In the crystal direction, the growth rate of the wafer is slow. <100> In the crystal direction, the growth rate of the part close to the center of the wafer is also slower. Therefore, the thickness of the inner area of the first sector area 21 is designed to be equal to the thickness of the inner area of the second sector area 22. This will not make the thickness value difference of the wafer too large, but also reduce the processing difficulty of the base.
[0061] In some embodiments, the angle between the upper surface of the edge region of the first sector 21 and the horizontal plane is in the range of 0.1° (deg)-0.5° (deg);
[0062] In this embodiment, the angle between the upper surface of the edge area of the first sector area 21 and the horizontal plane is designed to be 0.1°-0.5°, which can not only control the temperature difference between the base and the wafer, and then interact with the different thickness values produced by the different growth rates of the wafer to ensure that the overall thickness of the wafer is more uniform and improve the yield rate of the wafer, but also ensure that the edge area of the first sector area 21 provides sufficient support strength for the wafer 1.
[0063] Optionally, based on the above embodiments, the maximum thickness of the edge area of the first sector area 21 is in the range of 3 mm to 8 mm, the minimum thickness of the edge area of the first sector area 21 is in the range of 2 mm to 3 mm, and the thickness of the inner area of the first sector area 21 or the thickness of the second sector area 22 is in the range of 1 mm to 2 mm.
[0064] It should also be noted that due to the wafer <110> The growth rate of the epitaxial layer in the crystal direction is greater than that of the wafer <100> The growth rate of the epitaxial layer in the crystal direction, and from the wafer <110> Crystal to wafer <100> In the crystal direction, the growth rate of the epitaxial layer gradually decreases, and the <100> The epitaxial layer growth rate in the crystal direction is the lowest. <110> The epitaxial layer growth rate at the crystal direction is the highest.
[0065] Therefore, in an optional embodiment, the thickness of the second sector area 22 is determined by the <100> The radial direction corresponding to the crystal direction to the adjacent <100> Crystalline <110> The radial direction corresponding to the crystal orientation gradually increases, which can also achieve the effect of controlling the flatness of the wafer.
[0066] In another optional embodiment, the thickness of the edge region of the first sector region 21 is determined by the thickness of the wafer. <110> The radial direction corresponding to the crystal direction to the adjacent <110> Crystalline <100> The radial direction corresponding to the crystal orientation gradually decreases, which can also achieve the effect of controlling the flatness of the wafer.
[0067] In another optional embodiment, the thickness of the inner region of the first sector 21 is determined by the thickness of the wafer. <110> The radial direction corresponding to the crystal direction to the adjacent <110> Crystalline <100> The radial direction corresponding to the crystal orientation gradually decreases, which can also achieve the effect of controlling the flatness of the wafer.
[0068] It should also be noted that, based on the above three optional embodiments, it is also necessary to ensure that the minimum thickness of the edge area of the first sector area 21 is greater than the maximum thickness of the internal area of the first sector area 21, and to ensure that the minimum thickness of the edge area of the first sector area 21 is greater than the maximum thickness of the second sector area 22.
[0069] Through any combination of the above-mentioned optional embodiments, the temperature difference between the edge area and the center area of the base and the wafer can be controlled to be different, which in turn interacts with the different thickness values produced by the different growth rates of the wafer. By controlling the temperature difference, the growth rate of the edge of the wafer is reduced, and the overall thickness of the wafer is made more uniform, thereby improving the nano quality of the wafer and the yield rate.
[0070] In some embodiments, the sizes of the N first sector-shaped areas 21 are equal; the sizes of the N second sector-shaped areas 22 are equal.
[0071] As the wafer grows, each <110> In the crystal direction or each <100> In the crystal direction, the thickness of the wafer is relatively symmetrical, so the sizes of the N first sector areas 21 are designed to be equal, and the sizes of the N second sector areas 22 are designed to be equal.
[0072] Further optionally, the size of a first sector area 21 is equal to the size of a second sector area 22 , and when N is equal to 4, the sector angle between the first sector area 21 and the second sector area 22 is 45°.
[0073] In another optional embodiment, the size of a first sector area 21 may not be equal to the size of a second sector area 22. For example, the sector angle of the first sector area 21 is set within the range of 40° to 60°, and the angle of each first sector area 21 is equal. On this basis, the angle of each second sector area 22 is equal.
[0074] In some embodiments, in order to correspond to different crystal directions on the wafer, N first sector-shaped areas 21 and N second sector-shaped areas 22 are arranged alternately.
[0075] like Figure 4 As shown, an embodiment of the present invention further provides a device for epitaxial growth of wafers, the device being an epitaxial furnace, and the device comprising:
[0076] The base 3 for wafer epitaxial growth as described above;
[0077] A reaction chamber, wherein the reaction chamber is used to accommodate the base 3, wherein the base 3 divides the reaction chamber into an upper reaction chamber and a lower reaction chamber, and the wafer is placed in the upper reaction chamber.
[0078] The appearance of the device includes an upper quartz bell jar 4 and a lower quartz bell jar 5, and the upper quartz bell jar 4 and the lower quartz bell jar 5 are connected by a mounting component 6, and the interiors of the upper quartz bell jar 4 and the lower quartz bell jar 5 constitute a reaction chamber, wherein the portion between the upper quartz bell jar 4 and the base 3 is the upper reaction chamber, and the portion between the base 3 and the lower quartz bell jar 5 is the lower reaction chamber.
[0079] The exterior of the device also includes air intake and exhaust ports.
[0080] The device includes a base 3 and a base support rod 7 . The base support rod 7 is used to fix the base 3 and drive the base 3 to rotate, so that epitaxial growth can be carried out uniformly on the base 3 .
[0081] A heating bulb 8 responsible for providing reaction energy is arranged outside the upper quartz bell 4 and the lower quartz bell 5. The heating bulb 8 provides heat for the reaction by means of thermal radiation.
[0082] The heating bulb 8 is a halogen lamp.
[0083] It should be noted that the device for wafer epitaxial growth provided in an embodiment of the present invention is a device including the above-mentioned base for wafer epitaxial growth. All embodiments of the above-mentioned base for wafer epitaxial growth are applicable to the device and can achieve the same or similar technical effects.
[0084] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.
Claims
1. A susceptor for wafer epitaxial growth, characterized in that: include: A disc-shaped carrying structure for carrying wafers; The disk-shaped bearing structure includes N first sector areas and N second sector areas, wherein the first sector areas are shaped like the wafer. <110> The radial direction corresponding to the crystal direction is the central axis, and the second sector area is centered on the radial direction of the wafer. <100> The radial direction corresponding to the crystal orientation is the central axis, where N is a positive integer; The thickness of the edge region of each of the first sector-shaped areas is greater than the thickness of the inner region except the edge region; The thickness of each of the second sector-shaped areas is uniform.
2. The susceptor for wafer epitaxial growth according to claim 1, characterized in that: From the edge of the first sector-shaped area to the center of the first sector-shaped area, the thickness of the edge area of the first sector-shaped area gradually decreases.
3. The susceptor for wafer epitaxial growth according to claim 2, characterized in that: The minimum thickness of the edge region of the first sector-shaped area is greater than the thickness of the inner region of the first sector-shaped area.
4. The susceptor for wafer epitaxial growth according to any one of claims 1 to 3, characterized in that: The edge area of the first sector-shaped area is an area 3 mm to 10 mm away from the edge of the first sector-shaped area.
5. The susceptor for wafer epitaxial growth according to claim 1, characterized in that: The angle between the upper surface of the edge area of the first sector area and the horizontal plane is in the range of 0.1°-0.5°.
6. The susceptor for wafer epitaxial growth according to claim 1, characterized in that: The thickness of the inner region of the first sector-shaped area is equal to the thickness of the second sector-shaped area.
7. The susceptor for wafer epitaxial growth according to claim 1, characterized in that: The sizes of the N first sectors are equal; The sizes of the N second sectors are equal.
8. The susceptor for wafer epitaxial growth according to claim 1, characterized in that: The size of one of the first sectors is equal to the size of one of the second sectors.
9. The susceptor for wafer epitaxial growth according to claim 1, characterized in that: The N first sector-shaped areas and the N second sector-shaped areas are arranged alternately.
10. A device for wafer epitaxial growth, characterized in that: include: A susceptor for wafer epitaxial growth as claimed in any one of claims 1 to 9; A reaction chamber, the reaction chamber is used to accommodate the base; The base divides the reaction chamber into an upper reaction chamber and a lower reaction chamber, and the wafer is placed in the upper reaction chamber.