A cleaving system having a spring member for cleaving a semiconductor structure, and a method for cleaving such a structure

Abstract

To provide a novel cleavage system that results in cleavage structures with improved surface roughness characteristics and a method for cleaving that involves the use of such a cleavage system.SOLUTION: A cleavage system 5 is a system for cleaving a semiconductor structure and includes cleavage arms 9 that are movable from a start position to an elevated position where cleavage stress is applied to the semiconductor structure. A spring member 33 stores energy as the cleavage arm is raised, with the stored spring energy causing the structure to cleave into two parts at the start of cleavage across the structure.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] Cross-reference to related applications This application claims the benefit of U.S. Provisional Patent Application No. 62 / 906,860, filed Sep. 27, 2019, which is incorporated herein by reference in its entirety.

[0002] Disclosed field The field of the present disclosure relates to a cleaving system for cleaving a semiconductor structure, and more particularly to a cleaving system that uses stored spring energy to separate a semiconductor structure into two parts. The field of the present disclosure also relates to a method for cleaving a semiconductor structure by using such a cleaving system.

Background Art

[0003] Conventional cleaving systems use a suction cup under vacuum to grip the top and bottom surfaces of the structure to be cleaved. A series of upper suction cups that grip the top surface of the structure are connected to a cleaving arm. A motor applies an upward force to the cleaving arm, putting tension on the semiconductor structure. Once sufficient tension is applied, a blade is brought into contact with the periphery of the semiconductor structure to initiate cleavage. After cleavage is initiated, the cleaving arm moves upward and the cleavage propagates along the semiconductor structure from the edge where the blade contacted to the opposite edge.

[0004] The cleaving process separates the semiconductor structure into two parts. To fabricate a silicon-on-insulator structure by the cleaving process, a “donor” structure is separated from a layered structure, leaving a silicon device layer disposed on an insulator layer supported by a handle wafer. The quality of the surface of the resulting structure (e.g., surface roughness) depends on the quality of the cleavage.

[0005] Conventional cleavage methods often result in undesirable roughness patterns. When measured with an atomic force microscope, the greater roughness after cleavage causes a greater surface roughness in the finished structure (e.g., an SOI structure). The large cleavage roughness causes hillocks to form during epitaxial growth. Such hillocks are detected as bright point defects in the final inspection. Conventional cleavage methods also result in inconsistent cleavage tensile forces that cause the formation of surface roughness of the cleavage arc. Such a cleavage arc generally has an arc center on the cleavage start point side having an arc end perpendicular to the edge of the wafer. When the cleavage propagates across the wafer, as the arc approaches a point diametrically opposite the cleavage start point, the arc may become straight and reverse its curvature, and both ends of the arc remain perpendicular to the edge.

[0006] The quality of cleavage depends on a cleavage control system, the mass characteristics of the cleavage arm, motor characteristics, and control parameters including the initial tension and relative blade position. It is difficult to adjust these parameters to improve the quality of cleavage.

[0007] There is a need for a new cleavage system that provides a cleavage structure with improved surface roughness characteristics, and a cleavage method involving the use of such a cleavage system.

[0008] This section is intended to introduce the reader to various aspects of technologies that may be related to various aspects of the present disclosure as described and / or claimed below, and this discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of various aspects of the present disclosure. Accordingly, it should be understood that these descriptions are to be read from this perspective rather than as an admission of prior art. SUMMARY OF THE INVENTION

[0009] One aspect of the present disclosure is directed to a cleaving system for cleaving a semiconductor structure having a top surface and a bottom surface that is generally parallel to the top surface. The cleaving system includes a cleaving arm that is movable from a starting position to a raised position where a cleaving stress is applied to the semiconductor structure. The cleaving system includes a suction member for gripping the semiconductor structure at the top surface of the semiconductor structure. A suction rod extends through the cleaving arm. The suction rod is connected to the suction member toward the first end of the suction rod. A spring member applies a cleaving force to the semiconductor structure when the cleaving arm is in the raised position.

[0010] Another aspect of the present disclosure is directed to a cleaving system for cleaving a semiconductor structure having a top surface and a bottom surface that is generally parallel to the top surface. This cleaving system includes one or more suction cups for gripping the semiconductor structure at the top surface of the semiconductor structure. A suction rod is connected to the one or more suction cups toward the first end of the suction rod. A spring member applies a cleaving force to the semiconductor structure during cleaving. The suction rod extends through the spring member.

[0011] Yet another aspect of the present disclosure is directed to a method for cleaving a semiconductor structure having a top surface and a bottom surface that is generally parallel to the top surface. The top surface of the semiconductor structure is brought into contact with a suction cup. A vacuum is applied to the suction cup to grip the top surface of the semiconductor structure. A cleaving arm is moved from a starting position to a raised position to apply a cleaving force to the semiconductor structure at a spring member. The spring member stores spring energy when the cleaving arm is raised. The semiconductor structure is brought into contact with a blade to initiate cleavage of the semiconductor structure when the cleaving arm is in the raised position. The stored spring energy is released after the semiconductor structure is brought into contact with the blade, separating the semiconductor structure into two portions along a cleavage plane.

[0012] There are various improvements to the features described in connection with the above aspects of the present disclosure. Further features may also be incorporated into the above aspects of the present disclosure. These improvements and additional features may exist individually or in any combination. For example, the various features discussed below in connection with any of the illustrated embodiments of the present disclosure may be incorporated into any of the above aspects of the present disclosure, either alone or in any combination.

Brief Description of the Drawings

[0013]

Figure 1

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Figure 8

Mode for Carrying Out the Invention

[0014] Referring now to FIG. 1, a cleaving system 5 for cleaving a semiconductor structure S (FIG. 5) is shown. The cleaving system 5 includes a cleaving arm 9 and a suction member 13 extending from the cleaving arm 9 for gripping the semiconductor structure S. The suction member 13 extends from a suction rod 23 extending through the cleaving arm 9. The cleaving system 5 includes a spring member 33 that releases stored spring energy to separate the semiconductor structure, as further described below. To apply a tensile stress to the semiconductor structure S, the cleaving arm 9 moves from an initial position (FIG. 5) to a raised position (FIG. 6) where the spring member 33 and / or the cleaving arm 9 apply a cleaving force to the semiconductor structure S.

[0015] The semiconductor structure S to be cleaved in accordance with embodiments of the present disclosure can generally be any structure that cleaves upon application of a cleaving force to the semiconductor structure and at the start of cleavage (e.g., use of a blade contacting the periphery). Suitable structures can have a weakened zone formed within the structure, such as a weakened zone formed by ion implantation. Some structures include a layered silicon-on-insulator structure (e.g., having a donor wafer disposed on a dielectric layer and a handle wafer) that is cleaved to form a silicon-on-insulator structure (e.g., forming a silicon device layer on the dielectric layer disposed on the handle wafer by cleaving a donor wafer). The semiconductor structure S includes a top surface 41 (FIG. 5) and a bottom surface 43 that is generally parallel to the top surface 41. The semiconductor structure S also includes a periphery 45 extending from the top surface 41 to the bottom surface 43.

[0016] Cleavage system 5 includes a suction member 13 for gripping semiconductor structure S at upper surface 41 of semiconductor structure S toward cleavage propagation leading edge 21 (FIG. 5) of structure S. In the illustrated embodiment, suction member 13 is a suction cup. In other embodiments, an adhesive member may be used to connect chucks to each of the upper and lower surfaces of semiconductor structure S to apply a cleavage force to structure S. The illustrated embodiment includes first, second, and third suction members 13 for gripping upper surface 41 of semiconductor structure S toward cleavage propagation leading edge 21 of semiconductor structure S, but it should be understood that cleavage system 5 may include more or fewer suction members 13 (e.g., 1, 2, 3, 4, 5, or 6, or more suction members). Further, the illustrated embodiment includes first, second, and third suction rods 23, and first, second, and third spring members 33, but cleavage system 5 may include more or fewer suction rods 23 and / or spring members 33 (e.g., 1, 2, 3, 4, 5, or 6, or more suction rods 23, and / or 1, 2, 3, 4, 5, or 6, or more spring members 33).

[0017] Each suction member 13 is connected to a corresponding suction rod 23 toward a first end 53 (FIG. 2) of suction rod 23. Each suction rod 23 extends through cleavage arm 9. Cleavage arm 9 and suction rod 23 are movable relative to each other along suction rod axis A when cleavage arm moves from its starting position (FIG. 5) to its raised position (FIG. 6), and when the semiconductor structure is separated (FIG. 7) (FIGS. 3 and 4). Cleavage arm 9 includes a chamber 11 (FIG. 4) formed therein in which suction rod 23 moves relative to cleavage arm 9.

[0018] The suction rod 23 extends through the corresponding spring member 33. In the illustrated embodiment, the suction rod 23 is not connected to the splitting arm 9, and the splitting arm 9 and the suction rod 23 can move relative to each other along the suction rod axis A. The splitting system 5 includes upper and lower bearings 55, 49 (Figure 3; for example, linear bushings as shown) that allow the splitting arm 9 and the suction rod 23 to move relative to each other. The suction rod 23 moves within the bearings 49, 55 when the splitting arm moves from the starting position (Figure 5) to the raised position (Figure 6) and when releasing the spring energy accumulated during the splitting of the semiconductor structure (Figure 7). The seal member 19 (for example, a Teflon® pad) seals the chamber 11 in which the suction rod 23 moves relative to the splitting arm 9 to reduce particle contamination of the semiconductor structure S (Figure 4).

[0019] Each suction rod 23 is fluidly connected to the suction cup 13 to apply a vacuum between the suction cup 13 and the upper surface 41 (Figure 5) of the semiconductor structure S and includes a channel 25 (Figure 3) formed in the suction rod. The channel 25 is connected to a vacuum conduit 27 (Figure 1) that is fluidly connected to a vacuum source (for example, a vacuum pump). Once the vacuum is applied, the suction member 13 seals against the upper surface 41 of the semiconductor structure S.

[0020] Each spring member 33 is disposed between a collar 63 and the splitting arm 9. Each collar 63 extends radially outward from the respective suction rod 23 toward the second end 31 of the suction rod 23. The spring member 33 is at least partially received in a recess 51 (Figure 3) formed in the splitting arm 9. Each recess 51 has a floor portion 71 adjacent to the respective spring member 33. The spring member 33 is fixed by a retainer 57 (Figure 4) that functions as a stopper to prevent over-compression of the spring member 33. As shown in Figure 4, when the retainer 57 contacts the floor portion 71, the relative movement of the suction rod 23 and the splitting arm 9 is impeded.

[0021] In some embodiments, each color 63 is part of a color clamp 79. The color clamp 79 is adjustable such that the clamp 79 can be moved and refixed along the longitudinal axis A of the suction rod 23. In this way, the compression of the spring member 33 can be adjusted (for example, the pre-compression of the spring member 33 when at the starting position of the splitting arm 9 is adjustable). Changing the pre-compression of the spring member 33 can change the tensile force at the end of the spring energy release and can change the motion state and surface roughness of the cleave wave. Increasing the pre-compression increases the acceleration that is reduced when the spring releases energy. The matching between where the spring energy is minimized and when the rotation of the splitting arm begins when the spring energy decreases can also affect the final surface roughness.

[0022] In the illustrated embodiment, the spring member 33 is a helical compression spring that, when compressed (i.e., when the splitting arm 9 is raised), acts on the semiconductor structure S with a splitting force. In other embodiments, the spring member 33 is a tension spring (for example, the spring member is disposed under the splitting arm and connected to the splitting arm and a holding member disposed under the splitting arm). In still other embodiments, the spring member 33 is one or more disc springs (i.e., conical disc springs) such as a set of two or more stacked disc springs. In other embodiments, other spring members such as a compressed air spring, a compressed elastomer, or an extensible elastomer can be used.

[0023] As shown in FIG. 5, the splitting system 5 includes a first set of front suction members 13 (e.g., three suction members 13 as shown in FIG. 1) that grip the upper surface 41 of the semiconductor structure S at the front of the splitting propagation front edge 21 of the semiconductor structure S. The splitting system 5 also includes one or more rear suction members 15 (e.g., suction cups) that grip the upper surface 41 of the semiconductor structure S at the rear of the splitting propagation trailing edge 35 (i.e., the rear suction members 15 are disposed radially inward of the first set of suction members 13).

[0024] Since the splitting arm 9 moves to the raised position (FIG. 6) before the semiconductor structure S splits, the rear suction member 15 can be configured to accommodate the movement of the splitting arm 9. In some embodiments, the rear suction member 15 is a bellows suction cup that adjusts for changes in the distance between the splitting arm 9 and the semiconductor structure S. The bellows suction cup 15 includes a bellows section 37 (FIG. 1) that can flex and / or extend when the splitting arm 9 operates. The rear suction cup 15 is connected to a rear suction rod 39 that is connected to the splitting arm 9. The rear suction rod 39 can be rigid or flexible to allow the operation of the splitting arm 9.

[0025] Referring now to FIG. 5, in addition to the suction member 13 that grips the upper surface 41 of the semiconductor structure S, the splitting system 5 includes a set of one or more suction members 29 that grip the bottom surface 43 of the semiconductor structure S. The suction members 29 are connected to a suction rod 47 that is fixed in place (i.e., does not move) when the splitting arm 9 is raised.

[0026] According to an embodiment of the present disclosure, to split the semiconductor structure, the semiconductor structure S is set on the lower suction member 29 such that the lower suction member 29 contacts the bottom surface 43 of the semiconductor structure S (FIG. 5). The splitting arm 9 is lowered so that the upper surface 41 of the semiconductor structure S contacts the upper suction members 13, 15. A vacuum is applied to the lower suction member 29 to grip the bottom surface 43 of the semiconductor structure S. The vacuum also acts on the upper suction members 13, 15 via the vacuum conduit 27 and the channels 25 of the suction rods (FIG. 5) to grip the upper surface 41 of the semiconductor structure S.

[0027] After gripping the semiconductor structure S, the splitting arm 9 is moved from its starting position (FIG. 5) to its raised position (FIG. 6). The splitting arm 9 is connected to a swivel structure 59 (FIG. 1). The splitting system 5 includes a motor 67 that swivels the splitting arm 9 when the motor 67 is actuated. The splitting arm 9 swivels about a swivel axis P that extends through the swivel structure 59. The motor 67 can be connected to the swivel structure 59 by a chain or belt, or the motor 67 can be a direct drive motor incorporated into the swivel structure 59. The motor 67 can be a DC or AC servo motor and can optionally control the acceleration, deceleration, and / or speed of the splitting arm 9.

[0028] When the splitting arm 9 moves from its starting position (FIG. 5) to its raised position (FIG. 6), the splitting arm 9 moves the suction rod 23 axially upward. This compresses the spring member 33, applies a splitting force F (i.e., an upward force that facilitates splitting of the semiconductor structure) to the semiconductor structure S, and stores spring energy in the spring. According to some embodiments of the present disclosure, the splitting arm 9 is not rotated to the point where the spring is fully compressed and the spring retainer 57 contacts the splitting arm 9. Compression of the spring member 33 stores spring energy in the spring member 33 with the spring energy being released at the start of splitting. The splitting force F applied by the spring member 33 (and any additional force via the motor) is transmitted via the suction rod 23. At the raised position of the splitting arm 9, the lower suction member 29 applies a holding force to the semiconductor structure S, and the upper suction members 13, 15 apply an upward pulling force such that the semiconductor structure S is in a tensioned state. In some embodiments, the splitting force F applied by the spring member 33 is the only splitting force applied to the semiconductor structure S (e.g., upward forces other than the force applied via the spring member 33 are not used for splitting). In some embodiments, after splitting is propagated by the blade 61, the splitting arm is not moved upward (i.e., the spring member 33 continues to propagate splitting by releasing the stored energy).

[0029] Once the splitting arm 9 is in the raised position (Figure 6), the blade 61 is actuated to contact the blade with the periphery 45 of the semiconductor structure S. The blade 61 can contact the periphery near the damaged area in the semiconductor structure to facilitate splitting along the splitting plane. The blade 61 starts splitting along the splitting plane 65 (Figure 7) and separates the semiconductor structure S into two parts along the splitting plane 65. When the blade 61 starts splitting, the spring energy stored in the spring member 33 is released, and the suction rod 23 is moved upward through the splitting arm 9, which continues to separate the upper section 69 (Figure 7) of the semiconductor structure S from the lower section 73.

[0030] In some embodiments, the splitting system is configured to be adjustable to control the quality of splitting. For example, the system can include replaceable spring members with different spring constants to adjust the amount of energy released during accumulated splitting. In some embodiments, the splitting system includes different types of replaceable springs such as helical springs and stacked disc springs. The helical spring can provide a linear splitting force as a function of displacement, and the disc spring can provide a relatively constant suction cup force. Alternatively, or in addition to the above, the color clamp 79 described above can be moved along the longitudinal axis of the suction rod to change the stroke of the spring member 33 and the energy released during splitting propagation accumulated by the spring member 33.

[0031] Compared with conventional cleavage systems, the cleavage system of the present disclosure has several advantages. The use of a spring member in the present cleavage system enables the storage of spring energy when the cleavage arm rises. When cleavage is propagated by the blade, the energy of the spring is released to separate the semiconductor structure into two parts. This makes it possible for cleavage to depend on the stored spring energy rather than on the cleavage control system, the mass of the cleavage arm, and / or the characteristics of the motor. This makes the cleavage consistent during propagation, which can reduce the surface roughness of the cleaved surface and reduce the arc of cleavage. In an embodiment where the cleavage system includes a color clamp, the color clamp can be moved along the longitudinal axis of the suction rod to adjust the pre-compression of the spring member. In an embodiment where the cleavage assembly includes a bellows suction cup, the cleavage arm can move upward while still gripping the semiconductor structure S at the trailing edge of the cleavage propagation of the semiconductor structure. In other embodiments, the pre-compression can be increased or decreased by changing the design to relocate the spring attachment point.

Example

[0032] The process of the present disclosure is further illustrated by the following examples. These examples should not be viewed in a limiting sense. Example 1: Spring force and compression

[0033] FIG. 8 shows the total spring force as a function of spring compression. At the starting position of the cleavage arm, the spring energy is 3.61 pounds. The spring was compressed approximately 12 mm to generate a spring force of 6.5 pounds. As cleavage propagated and the spring energy was released to the pre-compression amount of 3.61 pounds. The spring was able to produce a maximum compression force of 6.971 pounds. For wafers cleaved with a force less than 6.971 pounds, the spring alone is sufficient for cleavage without the arm contributing to the cleavage force. In some embodiments, the end velocity of the suction cup at the end of cleavage (3.61 pounds) will approximate or match the starting rotational velocity of the cleavage arm.

[0034] As used herein, the terms "about," "substantially," "essentially," and "approximately," when used in combination with a range of dimensions, concentrations, temperatures, or other physical or chemical properties or characteristics, cover variations that may exist at the upper and / or lower limits of the range of the property or characteristic, including, for example, variations resulting from rounding, measurement methods, or other statistical fluctuations.

[0035] When introducing elements of the present disclosure or embodiments thereof, the articles "a," "an," "the," and "said" are intended to mean that one or more elements are present. The terms "comprising," "including," "containing," and "having" are intended to be inclusive and mean that additional elements other than the listed elements may exist. The use of terms indicating a particular orientation (e.g., "top," "bottom," "side," etc.) is for convenience of description and does not require any particular orientation of the items described.

[0036] Since various modifications can be made to the above-described configurations and methods without departing from the scope of the present disclosure, all matters included in the above description and the accompanying drawings should be construed as illustrative and not limiting for the purpose of assisting understanding.

Claims

1. A cleaving system for cleaving a semiconductor structure having a top surface and a bottom surface parallel to the top surface, comprising: a cleaving arm movable from a starting position to a raised position where a cleaving stress acts on the semiconductor structure; a suction member for gripping the semiconductor structure on the top surface of the semiconductor structure; a suction rod extending through the cleaving arm, wherein the suction rod is connected to the suction member at a first end of the suction rod; a spring member for applying a cleaving force to the semiconductor structure when the cleaving arm is in the raised position; The cleaving system comprising the above.

2. The cleaving system according to claim 1, wherein the suction rod extends through the spring member.

3. The cleaving system according to claim 1, wherein the spring member is a compression spring.

4. The cleaving system according to claim 1, wherein the spring member is a disc spring.

5. The cleaving system according to claim 1, wherein the spring member is a tension spring, and the spring member is disposed under the cleaving arm.

6. The cleaving system according to claim 1, wherein the suction member is a suction cup, and the suction rod includes a channel formed therein and fluidly connected to the suction cup for applying a vacuum to the suction cup.

7. The suction member is a first suction member, the suction rod is a first suction rod, the spring member is a first spring member, and the cleaving system further comprises: a second suction member for gripping the semiconductor structure; a second suction rod extending through the cleaving arm, wherein the second suction rod is connected to the second suction member at a first end of the second suction rod; a second spring member for applying a cleaving force to the semiconductor structure when the cleaving arm is in the raised position. The cleaving system according to claim 1, comprising the above.

8. a third suction member for gripping the semiconductor structure; a third suction rod extending through the cleaving arm, wherein the third suction rod is connected to the third suction member at a first end of the third suction rod; a third spring member for applying a cleaving force to the semiconductor structure when the cleaving arm is in the raised position. The cleaving system according to claim 7, further comprising the above.

9. The cleaving arm pivots about a pivot axis to move the cleaving arm between the starting position and the raised position, and the cleaving system includes a motor for pivoting the cleaving arm in operation of the motor. The cleaving system according to claim 1.

10. The cleavage system according to claim 9, further comprising a bellows suction cup connected to the cleavage arm, the bellows suction cup being disposed radially inward with respect to the suction member.

11. The cleavage system according to claim 1, wherein the suction rod is not connected to the cleavage arm.

12. The cleavage system according to claim 1, comprising one or more suction members for gripping the semiconductor structure at the bottom surface of the semiconductor structure.

13. A cleavage system for cleaving a semiconductor structure having a top surface and a bottom surface parallel to the top surface, one or more suction cups for gripping the semiconductor structure at the top surface of the semiconductor structure; a suction rod connected to the one or more suction cups at a first end of the suction rod; a spring member that applies a cleavage force to the semiconductor structure during cleavage, wherein the suction rod extends through the spring member; A cleavage system comprising:

14. The cleavage system according to claim 13, further comprising a bellows suction cup configured to contact the top surface of the semiconductor structure, the bellows suction cup being disposed radially inward with respect to the one or more suction cups.

15. A method for cleaving a semiconductor structure having a top surface and a bottom surface parallel to the top surface, contacting the top surface of the semiconductor structure with a suction cup; applying a vacuum to the suction cup to grip the top surface of the semiconductor structure; moving a cleavage arm from a starting position to a raised position to apply a cleavage force to the semiconductor structure in a spring member, wherein the spring member stores spring energy when the cleavage arm is raised; contacting the semiconductor structure with a blade to initiate cleavage of the semiconductor structure when the cleavage arm is in the raised position; releasing the stored spring energy after contacting the semiconductor structure with the blade to separate the semiconductor structure into two parts along a cleavage plane; A method comprising:

16. The method according to claim 15, wherein the suction cup is connected to a suction rod extending through the cleavage arm, and the suction rod extends through the spring member.

17. When the cleavage arm moves to the raised position, the cleavage arm moves axially upward in the direction of the suction rod axis, When the semiconductor structure is separated into two parts, the suction rod moves axially downward with respect to the cleavage arm. The method according to claim 16.

18. The cleavage force applied by the spring member is transmitted via the suction rod, and the cleavage force applied by the spring member is the only cleavage force acting on the semiconductor structure, the method according to claim 16. **Claim 19** The cleavage arm does not move during the propagation of cleavage, the method according to claim 15.

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