Crystal wafer and process for forming the same

Abstract

To disclose methods of forming a crystalline wafers or films such as a diamond wafer or film.SOLUTION: A method disclosed herein may include creating a damaged layer in a seed wafer at a depth from a seed wafer upper surface. The seed wafer may include a diamond crystalline structure. The method may also include growing a diamond epitaxial layer on the seed wafer upper surface via a chemical vapor deposition (CVD) process. A growth temperature of the CVD process may convert the damaged layer into a graphitized interface between the seed wafer and the diamond epitaxial layer. The method may further include applying light from a laser to the graphitized interface to separate the diamond epitaxial layer from the seed wafer and obtain the diamond wafer.SELECTED DRAWING: Figure 1

Description

[Background technology]

[0001]

[0001] Single crystal diamond wafers can be grown using chemical vapor deposition (CVD) processes. Such processes can successfully grow relatively thick (e.g., 10 mm) wafers. However, conventional slicing techniques, such as sawing, laser sawing, and / or etching, have proven problematic. For example, conventional slicing techniques can result in significant cutting loss. Conventional etching techniques can be too time-consuming (e.g., etching periods on the order of several days) to be economically feasible. Summary of the Invention

[0002]

[0002] Shown and / or described in connection with at least one of the drawings, and more fully described in the claims, is a process that includes, inter alia, creating a damage layer below a top surface of a seed wafer, annealing the damage layer to form a graphitized interface below the top surface of the seed wafer, and laser cleaving the seed wafer along the graphitized interface to separate a diamond film or diamond wafer from the seed wafer. Such a technique may have reduced cutting losses, be more time efficient, and / or have other advantages over conventional techniques.

[0003]

[0003] These and other advantages, aspects and novel features of the present disclosure, as well as details of illustrated embodiments thereof, will be more fully understood from the following description and drawings. [Brief explanation of the drawings]

[0004]

[0004] The various features and advantages of the present disclosure may be more readily understood by reference to the following detailed description, taken in conjunction with the accompanying drawings, in which like reference numerals indicate like structural elements and in which: [Figure 1]

[0005] 1 is a flowchart of a process for forming a diamond wafer or film from a seed wafer according to various aspects of the present disclosure. [Figure 2]

[0006] 2A-2D are cross-sectional views of a seed wafer at various stages of the process of FIG. 1; [Figure 3]

[0007] 2A-2D are perspective views of a seed wafer at various stages of the process of FIG. 1. [Figure 4]

[0008] FIG. 1 shows ion species and their respective energy ranges, dose ranges, and depths at the depicted maximum and minimum doses. [Figure 5]

[0009] FIG. 10 shows the ion species and their respective energy ranges, dose ranges, and vacancy damage at the depicted maximum dose. DETAILED DESCRIPTION OF THE INVENTION

[0005]

[0010] The following description provides various examples of providing diamond wafers or films. Such examples are non-limiting, and the appended claims should not be limited to the particular examples disclosed. In the following discussion, the terms "example" and "for example" are not limiting.

[0006]

[0011] The figures show general configuration schemes, and descriptions and details of well-known features and techniques may be omitted to avoid unnecessarily obscuring the present disclosure. Additionally, elements in the figures are not necessarily drawn to scale. For example, the dimensions of some elements in the figures may be exaggerated relative to other elements to help better understand the examples discussed in this disclosure. The same reference numbers in different figures refer to the same elements.

[0007]

[0012] The term "and / or" means any one or more of the items in the list joined by "and / or." As an example, "x and / or y" means any elements of the three-element set {(x),(y),(x,y)}. As another example, "x,y and / or z" means any elements of the seven-element set {(x),(y),(z),(x,y),(x,z),(y,z),(x,y,z)}.

[0008]

[0013] The terms "comprises," "comprising," "includes," and / or "including" are "open-ended" terms that specify the presence of stated features but do not exclude the presence or addition of one or more other features.

[0009]

[0014] Terms such as "first," "second," and the like may be used herein to describe various elements, but these elements should not be limited by these terms. These terms are used only to distinguish one element from another. Thus, for example, a first element discussed in this disclosure could be referred to as a second element without departing from the teachings of the disclosure.

[0010]

[0015] Unless otherwise specified, the term "coupled" may be used to describe two elements that are in direct contact with each other or two elements that are indirectly connected by one or more other elements. For example, if element A is coupled to element B, element A may be in direct contact with element B or indirectly connected to element B by an intervening element C. Similarly, the terms "above" or "on" may be used to describe two elements that are in direct contact with each other or two elements that are indirectly connected by one or more other elements.

[0011]

[0016] In general, aspects of the present disclosure are directed to a process for forming a crystalline wafer or film. Such a process may include generating a damage layer in a seed wafer at a depth from the top surface of the seed wafer and forming a crystalline structure on the top surface of the seed wafer. The method may also include irradiating the damage layer with light from a laser and separating the formed crystalline structure from the seed wafer to obtain a wafer. More specifically, the seed wafer may include a diamond crystalline structure. Forming the crystalline structure may include growing a diamond epitaxial layer on the top surface of the seed wafer by a chemical vapor deposition (CVD) process. The growth temperature of the CVD process can convert the damage layer into a graphitized interface between the seed wafer and the diamond epitaxial layer. Irradiating the light from the laser can separate the diamond epitaxial layer from the seed wafer to obtain a diamond wafer.

[0012]

[0017] Referring now to Figures 1 through 3, a process 100 for forming a diamond wafer or film is shown. While process 100 is shown and described below specifically with respect to forming a diamond wafer or film, process 100 may also be used to form wafers or films of crystalline materials other than diamond. At 110, a seed wafer 10 is prepared for ion implantation. Seed wafer 10 may include a seed wafer top surface 12, a seed wafer bottom surface 14, and a seed wafer side surface 16 between seed wafer top surface 12 and seed wafer bottom surface 14. At 110, seed wafer top surface 12 may be polished to remove surface defects in the diamond crystalline structure of seed wafer 10.

[0013]

[0018] At 120, a damage layer 20 can be created below the seed wafer top surface 12. To this end, ions 22 can be implanted through the seed wafer top surface 12 to a desired depth D within the seed wafer 10. Such implantation can damage the diamond crystal structure and create bond vacancies within the diamond crystal structure of the seed wafer 10. Various ion species can be implanted. In particular, hydrogen, helium, and / or carbon ions can be implanted through the seed wafer top surface 12 to a depth below the seed wafer top surface 12, depending on the ion species and implantation energy.

[0014]

[0019] As shown in the table of Figure 4, hydrogen ions can be implanted using implant energies ranging from 20 kiloelectron volts (keV) to 525 keV, which correspond to peak concentration implant depths of between 0.1 microns (μm) and 3.0 μm, respectively, into the diamond crystalline structure of the seed wafer 10. Similarly, helium ions can be implanted using implant energies ranging from 20 keV to 1220 keV, which correspond to peak concentration implant depths of between 0.2 μm and 2.0 μm, respectively, into the diamond crystalline structure of the seed wafer 10. Furthermore, carbon ions can be implanted using implant energies ranging from 80 keV to 1220 keV, which correspond to peak concentration implant depths of between 0.1 μm and 1.6 μm, respectively, into the diamond crystalline structure of the seed wafer 10.

[0015]

[0020] 4 further provides a first graph of concentration versus depth for hydrogen, helium, and carbon ion species at the maximum ion implantation energies and maximum doses listed in the table. FIG. 4 further provides a second graph of concentration versus depth for hydrogen, helium, and carbon ion species at the minimum ion implantation energies and minimum doses listed in the table. The graphs are based on simulation data.

[0016]

[0021] Furthermore, as shown in Figure 5, the concentration of vacancy bonds at implantation depth depends on the implantation dose of various ion species. In particular, hydrogen ions have a dose of 1e14 ions / cm 2 From this, it is 1.2e17 ions / cm 2 Helium ions can be implanted at doses ranging from 1e13 ions / cm 2 From this, it is 1.2e17 ions / cm 2 Carbon ions can be implanted at doses ranging from 1e12 to 2.0e16. The graph in Figure 5 shows vacancies versus implant depth for carbon and helium ions at the maximum implant energies and doses listed, respectively. As shown, the implant energy and dose can result in peak vacancies of approximately 2.5e23 per cubic centimeter. Again, the graph is based on simulated data.

[0017]

[0022] At 130, process 100 grows an epitaxial layer 30 on seed wafer 10. To this end, process 100 may use a crystal growth process suitable for growing an epitaxial layer 30 of diamond on seed wafer top surface 12. Such growth may result in the formation of grains whose crystalline structure aligns with that of seed wafer 10 and continues such crystalline structure beyond seed wafer top surface 12.

[0018]

[0023] In various embodiments, a chemical vapor deposition (CVD) process may be used to grow the epitaxial layer 30. Such a CVD process may be performed at a growth temperature (e.g., 1100 to 1150° C.) sufficient to anneal the damaged layer 20 and convert it to graphite. Such conversion to graphite effectively provides a graphitized interface 24 between the diamond crystalline structure of the seed wafer 10 and the diamond crystalline structure of the epitaxial layer 30.

[0019]

[0024] After forming the epitaxial layer 30 and forming the graphitized interface 24, the process 100 can separate the epitaxial layer 30 from the seed wafer 10 at 140. To this end, the process 100 can include focusing light emitted from a laser 50 at the graphitized interface 24 to break the bonds at the graphitized interface 24 and separate the epitaxial layer 30 from the seed wafer 10. In various embodiments, the graphitized interface 24 provides an opaque layer within an otherwise transparent structure. Due to the opaque nature of the graphitized interface 24, the laser 50 can be absorbed by the graphitized interface 24 and break the bonds at the graphitized interface 24. Thus, the effect of the laser 50 is localized to the graphitized interface 24, thus avoiding further damage to the crystalline structure of the epitaxial layer 30 and / or the seed wafer 10.

[0020]

[0025] At 150, process 100 can output a new diamond wafer or film by finishing the detached epitaxial layer 30. In particular, process 100 can polish and / or etch the underside of the detached epitaxial layer 30 to remove remnants of the graphitized interface 24. Such polishing and / or etching can also remove and / or reduce defects along the graphitized interface 24.

[0021]

[0026] As shown in FIGS. 2 and 3, the process 100 can be repeated to reuse the seed wafer 10.

[0027] While the present disclosure includes reference to particular examples, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the scope of the present disclosure. Additionally, modifications may be made to the disclosed examples without departing from the scope of the present disclosure. Accordingly, the present disclosure is not limited to the disclosed examples, but is intended to include all examples that fall within the scope of the appended claims.

Claims

1. A method of forming a wafer, comprising: generating a damage layer in the seed wafer at a depth from an upper surface of the seed wafer; forming a crystalline structure on the top surface of the seed wafer; irradiating the damage layer with light from a laser to separate the formed crystalline structure from the seed wafer, thereby obtaining the wafer; Including, forming the crystalline structure includes growing an epitaxial layer using a chemical vapor deposition (CVD) process; The method wherein the deposition temperature of the CVD process converts the damaged layer to graphite.

2. A method as described in claim 1, wherein the growth temperature of the CVD process forms the damage layer at the graphitized interface.

3. 2. The method of claim 1, wherein creating the damage layer comprises implanting ions into the seed wafer through a top surface of the seed wafer.

4. 2. The method of claim 1, wherein creating the damage layer comprises implanting helium ions into the seed wafer through a top surface of the seed wafer.

5. 2. The method of claim 1, wherein creating the damage layer comprises implanting hydrogen ions into the seed wafer through the top surface of the seed wafer.

6. 2. The method of claim 1, wherein creating the damage layer comprises implanting carbon ions into the seed wafer through a top surface of the seed wafer.

7. 10. The method of claim 1, wherein a growth temperature of the CVD process anneals the damaged layer.

8. 2. The method of claim 1, further comprising removing remnants of the damaged layer from the wafer.

9. 10. The method of claim 1, further comprising polishing the underside of the wafer.

10. 10. The method of claim 1, comprising etching the underside of the wafer.

11. 10. The method of claim 1, comprising the step of reusing the seed wafer to form another wafer after separating the wafer from the seed wafer.

12. 10. The method of claim 1, the seed wafer comprises a diamond crystalline structure; the wafer separated from the seed wafer comprises a diamond crystalline structure; method.

13. 1. A method of forming a diamond wafer, comprising: generating a damage layer in a seed wafer at a depth from a top surface of the seed wafer, the seed wafer comprising a diamond crystalline structure; growing a diamond epitaxial layer on top of the seed wafer by a chemical vapor deposition (CVD) process, the growth temperature of the CVD process converting the damaged layer into a graphitized interface; irradiating the graphitized interface with light from a laser to separate the diamond epitaxial layer from the seed wafer to obtain the diamond wafer; A method comprising:

14. 14. The method of claim 13, wherein creating the damage layer comprises implanting ions into the seed wafer through a top surface of the seed wafer.

15. 15. The method of claim 14, wherein the ions include one or more of helium, hydrogen, and carbon ions.

16. 14. A method according to claim 13, comprising the step of removing remnants of the graphitized interface from the diamond wafer.

17. 14. The method of claim 13, comprising polishing the underside of the diamond wafer.

18. 14. The method of claim 13, comprising etching the underside of the diamond wafer.

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