JP2009272314A - Multilayer silicon semiconductor wafer and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multilayer silicon semiconductor wafer capable of having gettering capability in a multilayer silicon semiconductor wafer where thin-layer silicon semiconductor wafers are laminated, and to provide a manufacturing method of the multilayer silicon semiconductor wafer. <P>SOLUTION: The multilayer silicon semiconductor wafer is manufactured by polishing the backside of a silicon semiconductor wafer of which devices have already been formed for thinning, forming a damage layer on the polishing surface on the backside of the thinned silicon semiconductor wafer for manufacturing individual silicon semiconductor wafers, and laminating a plurality of individual silicon semiconductor wafers where the plurality of devices have already been formed and the damage layer is formed on the backside. In the multilayer silicon semiconductor wafer, each laminated layer has each individual device and damage layer, and even a multilayer structure of a thin layer has gettering capability. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a gettering method that is a technique for removing heavy metal impurities that adversely affect device operation, and relates to a multilayer silicon semiconductor wafer having high gettering capability and a method for manufacturing the same.

  As the density of devices such as semiconductor integrated circuits is increased and the integration is increased, stabilization of device operation has been desired. In particular, improvement of characteristic values such as leakage current and oxide film breakdown voltage is an important issue.

  However, in the manufacturing process of semiconductor integrated circuits, the possibility of contamination with impurities such as undesired heavy metals such as Cu, Fe, and Ni cannot be denied. It is widely known that these heavy metal impurities are significantly dissolved in the silicon single crystal and the above-described leakage current and oxide film breakdown voltage characteristics are remarkably deteriorated.

  Therefore, various gettering techniques have been developed as a method for removing these heavy metal impurities out of the device operating region. For example, oxygen atoms contained in a silicon single crystal produced by the CZ method are deposited, and an IG (Internal Gettering) method that captures heavy metals in the strain around the precipitate, or a polycrystalline silicon film is formed on the back surface of a silicon wafer And a method of trapping impurities in the distortion of the polycrystalline grain boundary. The latter is a representative example of the EG method (External Gettering) method. A technique for gettering impurities in a silicon semiconductor wafer with a metal layer or an oxide layer is also known (for example, Patent Documents 1 to 4).

However, as one of the methods for highly integrating devices, recently, after fabricating a device on a normal silicon wafer, the back surface is polished to form a thin film, and the thin film silicon wafer thus manufactured is deposited in a plurality of layers. (For example, Japanese Patent Application No. 2007-176310). This structure is called a multi-chip package (MCP), but this structure has the advantage that higher integration is possible than conventional methods because multiple devices can be formed in the depth direction of the wafer. In this case, the metal collects in the lattice distortion of the device region formed in each layer, and there is a disadvantage that operation failures increase. In terms of cost, all the layers are defective, so the loss is large. Moreover, in this structure, conventional impurity gettering techniques such as the backside polycrystalline silicon layer and the IG method do not function effectively. In the former, the device layer existing in each layer interferes with the diffusion process of metal impurities to the backside polycrystalline layer, and in the latter, the BMD (Bulk Micro Defect) layer that can be a gettering site is scraped off by polishing. The fact that almost no gettering layer remains is the reason why gettering does not function.
JP 2002-323795 JP 2004-327489 A JP-A-2005-64341 JP2005-311126

  The present invention has been made in view of such problems, and a multi-layer silicon semiconductor capable of providing a gettering capability even in a multi-layer silicon semiconductor wafer formed by laminating thin silicon semiconductor wafers. An object of the present invention is to provide a wafer and a manufacturing method thereof.

  In order to solve the above problems, the multilayer silicon semiconductor wafer of the present invention is formed by polishing the back surface of a silicon semiconductor wafer on which devices have been formed, and forming a damaged layer on the back surface of the thinned silicon semiconductor wafer. A multi-layered silicon semiconductor wafer produced by laminating a plurality of individual silicon semiconductor wafers having individual devices formed and having a damaged layer formed on the back surface, wherein each of the laminated layers is Each device has an individual device and a damage layer, and has a gettering ability even in a thin multilayer structure. A semiconductor device according to the present invention comprises the above-described multilayer silicon semiconductor wafer.

  The method for producing a multilayer silicon semiconductor wafer of the present invention comprises a step of polishing and thinning the back surface of a silicon semiconductor wafer on which devices have been formed, and forming a damage layer on the back surface of the thinned silicon semiconductor wafer to form individual layers. A step of fabricating a silicon semiconductor wafer, and a step of laminating a plurality of individual silicon semiconductor wafers on which the device has been formed and a damage layer is formed on the back surface, and each of the laminated layers is an individual device and A multilayer silicon semiconductor wafer having a damaged layer and having a gettering ability even in a thin multilayer structure is manufactured. The method for producing a semiconductor device of the present invention is the above method, wherein a multilayer silicon semiconductor wafer is used as the semiconductor device.

  It is preferable to form the damaged layer by sandblasting, by mechanical grinding, or by leaving polishing scratches or damage on the back surface by laser irradiation. The damaged layer can be formed by laser irradiation.

  In order to remove harmful impurities in each layer of the multilayer structure, it is necessary to provide a gettering layer at the bottom of each layer. However, in the current MCP process, there is no layer that can be regarded as a gettering layer after the film is thinned. Therefore, the contaminated impurity metal usually enters the device layer. This is because the device layer is more distorted than the single crystal silicon region, and impurity metals are deposited in the device layer.

  The present invention has been devised in view of this point, and is characterized by forming a damage layer (also referred to as a strained layer) on the back surface of a thinned silicon wafer. As a method of forming this damaged layer (strained layer), for example, a method of forming strain by colliding alumina powder or silica powder with the back surface, such as a sandblast method, is effective. A method using mechanical grinding to form the film can also be used sufficiently. Furthermore, a strained layer (damaged layer) can be formed by laser irradiation.

  According to the multilayer silicon semiconductor wafer of the present invention, effective gettering ability can be imparted even in a thin multilayer structure. Moreover, according to the method of the present invention, there is an advantage that the multilayer silicon semiconductor wafer of the present invention can be effectively produced.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. However, these embodiments are shown as examples, and various modifications can be made without departing from the technical idea of the present invention. Not too long. FIG. 1 is a flowchart showing a process sequence of a method for producing a multilayer silicon semiconductor wafer according to the present invention. FIG. 2 is a schematic explanatory view showing a production procedure of the method for producing a multilayer silicon semiconductor wafer of the present invention. FIG. 3 is a cross-sectional explanatory view showing the structure of the multilayer silicon semiconductor wafer of the present invention.

  The method for manufacturing a multilayer silicon semiconductor wafer of the present invention includes manufacturing steps as shown in FIGS. First, a plurality of (three in the example of FIG. 2) silicon semiconductor wafers 10, 10, 10 on which devices have been formed are prepared (step 100 in FIG. 1 and FIG. 2 (a)). Next, the back surface of the silicon semiconductor wafer 10 is polished to thin the silicon semiconductor wafer 10. That is, the back surface portion 10b is removed by grinding the back surface of the silicon semiconductor wafer 10 to obtain a thinned silicon semiconductor wafer 10a (step 102 in FIG. 1 and FIG. 2B).

  Subsequently, a damage layer 12 is formed on the thinned silicon semiconductor wafer 10a to produce individual silicon semiconductor wafers 10c (step 104 in FIG. 1 and FIG. 2C). As a method of forming the damaged layer 12 on the back surface of the silicon semiconductor wafer 10a, for example, a method of forming strain by colliding alumina powder or silica powder with the back surface, such as sandblasting, is effective. At this time, a method using mechanical grinding can be sufficiently used to form a strain. Furthermore, the strained layer (damaged layer) 12 can be formed by laser irradiation.

  A plurality (three in the illustrated example) of individual silicon semiconductor wafers 10c on which the device has been formed and the damage layer 12 is formed on the back surface are stacked and bonded together (step 106 in FIG. 1 and FIG. 2 (d)). In this way, the multi-layered silicon semiconductor wafer 10d is completed (step 108 in FIG. 1 and FIG. 2E).

  FIG. 3 is an enlarged cross-sectional explanatory view of the multilayer silicon semiconductor wafer 10d. The individual silicon semiconductor wafers 10c having three devices already formed and the damage layer 12 formed on the back surface are stacked and bonded together using an adhesive to produce a multilayer silicon semiconductor wafer 10d. This multi-layered silicon semiconductor wafer 10d was confirmed to have a high gettering capability as described in the examples described later.

  Hereinafter, although an example and a comparative example of the present invention are given and explained concretely, the present invention is not limited to these.

Example 1
A crystal rod having a diameter of 6 inches, an initial oxygen concentration of 14 ppma JEIDA, and an orientation <100> was pulled at a normal pulling speed (1.2 mm / min) by the CZ method. This crystal rod was processed into a silicon semiconductor wafer, and a device was formed on the surface. Next, a silicon semiconductor wafer having a reduced thickness was obtained by polishing the back surface of this device-formed silicon semiconductor wafer to a thickness of 50 μm. By applying sand blasting to the back surface of the thinned silicon semiconductor wafer, a strained layer (damage layer) is formed, three individual silicon semiconductor wafers are produced, and the three individual silicon semiconductor wafers are stacked and an adhesive is used. And pasted together.

Fe was applied at a concentration of 4 × 10 ¹³ cm ⁻² to the surface of the multi-layered silicon semiconductor wafer thus laminated, and Fe was diffused into the multi-layered silicon semiconductor wafer by heat treatment at 1000 ° C. for 1 hour. Thereafter, heat treatment was performed at 600 ° C. for 10 hours, and the depth direction distribution of Fe concentration was measured by SIMS from the surface of the multilayer silicon semiconductor wafer after cooling to room temperature. As a result, it was confirmed that Fe was below the lower limit of detection in the single crystal silicon portion of the multilayer silicon semiconductor wafer, whereas Fe was distributed in a high concentration in the damaged layer (sandblast portion) of the multilayer silicon semiconductor wafer. It was. This is seen in all three layers having a multilayer structure of the multilayer silicon semiconductor wafer, and it is considered that a damaged layer (strained layer) formed on the back surface of each layer exhibited a strong gettering ability.

(Example 2)
A crystal rod having a diameter of 6 inches, an initial oxygen concentration of 14 ppma JEIDA, and an orientation <100> was pulled at a normal pulling speed (1.2 mm / min) by the CZ method. This crystal rod was processed into a silicon semiconductor wafer, and a device was formed on the surface. Subsequently, the back surface of this device-formed silicon semiconductor wafer was mechanically ground to a thickness of 50 μm to form a strained layer (damaged layer) and a thinned silicon semiconductor wafer. Three individual silicon semiconductor wafers were prepared, and the three individual silicon semiconductor wafers were stacked and bonded together using an adhesive.

Fe was applied at a concentration of 4 × 10 ¹³ cm ^{−2 on} the surface of the multi-layered silicon semiconductor wafer thus stacked, and Fe was diffused inside the wafer by heat treatment at 1000 ° C. for 1 hour. Thereafter, heat treatment was performed at 600 ° C. for 10 hours, and the depth direction distribution of Fe concentration was measured by SIMS from the surface of the multilayer silicon semiconductor wafer after cooling to room temperature. As a result, it was confirmed that Fe was below the lower limit of detection in the single crystal silicon portion of the multilayer silicon semiconductor wafer, whereas Fe was distributed at a high concentration on the back side, which is the ground surface of the multilayer silicon semiconductor wafer. It was. This is seen in all three layers having a multilayer structure of the multilayer silicon semiconductor wafer, and it is considered that the strained layer (damage layer) formed on the back surface of each layer exhibited a strong getter ability.

(Example 3)
A crystal rod having a diameter of 6 inches, an initial oxygen concentration of 14 ppma JEIDA, and an orientation <100> was pulled at a normal pulling speed (1.2 mm / min) by the CZ method. This crystal rod was processed into a silicon semiconductor wafer, and a device was formed on the surface. Next, a silicon semiconductor wafer having a reduced thickness was obtained by polishing the back surface of this device-formed silicon semiconductor wafer to a thickness of 50 μm. The back surface of the thinned silicon semiconductor wafer is irradiated with a YAG laser at an energy density of 10 J / cm ² to form a strained layer (damage layer), and three individual silicon semiconductor wafers are produced. These three individual silicon semiconductors The wafers were stacked and bonded using an adhesive.

Fe was applied at a concentration of 4 × 10 ¹³ cm ⁻² to the surface of the multi-layered silicon semiconductor wafer thus laminated, and Fe was diffused into the multi-layered silicon semiconductor wafer by heat treatment at 1000 ° C. for 1 hour. Thereafter, heat treatment was performed at 600 ° C. for 10 hours, and the depth direction distribution of Fe concentration was measured by SIMS from the surface of the multilayer silicon semiconductor wafer after cooling to room temperature. As a result, while Fe was below the lower limit of detection in the single crystal silicon portion of the multilayer silicon semiconductor wafer, Fe was distributed at a high concentration in the strained layer (damage layer) portion of the multilayer silicon semiconductor wafer that was irradiated with laser. It was confirmed. This is seen in all three layers having a multilayer structure of the multilayer silicon semiconductor wafer, and it is considered that the strained layer (damage layer) formed on the back surface of each layer exhibited a strong getter ability.

(Comparative Example 1)
A crystal rod having a diameter of 6 inches, an initial oxygen concentration of 14 ppma JEIDA, and an orientation <100> was pulled at a normal pulling speed (1.2 mm / min) by the CZ method. The crystal rod was processed into a silicon semiconductor wafer, and the back surface of the silicon semiconductor wafer was polished to a thickness of 50 μm to obtain a silicon semiconductor wafer having a reduced thickness. The three thinned silicon semiconductor wafers were stacked and bonded using an adhesive to form a single multilayer silicon semiconductor wafer.

Fe was applied at a concentration of 4 × 10 ¹³ cm ^{−2 on} the surface of the multilayer silicon semiconductor wafer thus laminated, and Fe was diffused into the multilayer silicon semiconductor wafer by heat treatment at 1000 ° C. for 1 hour. Thereafter, heat treatment was performed at 600 ° C. for 10 hours, and the depth direction distribution of Fe concentration was measured by SIMS from the surface of the multilayer silicon semiconductor wafer after cooling to room temperature. As a result, Fe was detected from the surface, and its value of 3 × 10 ¹⁵ cm ⁻³ did not change even near the back surface of the multilayer silicon semiconductor wafer, and moved to the second layer counted from the surface of the multilayer silicon semiconductor wafer. However, the density did not change, and it was found that the multilayer silicon semiconductor wafer was uniformly distributed in the depth direction. This indicates that the multilayer silicon semiconductor wafer does not have a portion that can be a gettering layer.

  The present invention is not limited to the above embodiment. The above embodiment is an exemplification, and the present invention has any configuration that has substantially the same configuration as the technical idea described in the claims of the present invention and that exhibits the same effects. Are included in the technical scope.

  For example, in the present invention, the strained layer forming method used is not limited to sandblasting, mechanical grinding, or laser irradiation. Needless to say, other damage layer forming methods are also included in the scope of the present invention.

It is a flowchart which shows the process order of the manufacturing method of the multilayer silicon semiconductor wafer of this invention. It is typical explanatory drawing which shows the preparation procedure of the manufacturing method of the multilayer silicon semiconductor wafer of this invention. It is sectional explanatory drawing which shows the structure of the multilayer silicon semiconductor wafer of this invention.

Explanation of symbols

  10: silicon semiconductor wafer, 10a: thinned silicon semiconductor wafer, 10b: deleted back surface portion, 10c: individual silicon semiconductor wafer, 10d: multilayer silicon semiconductor wafer, 12: damaged layer.

Claims (6)

  The back surface of the silicon semiconductor wafer on which the device has been formed is polished to form a thin film, and a damaged layer is formed on the back polished surface of the thinned silicon semiconductor wafer to produce an individual silicon semiconductor wafer. A multilayer silicon semiconductor wafer produced by laminating a plurality of individual silicon semiconductor wafers each having a damaged layer formed thereon, each of the laminated layers having an individual device and a damaged layer, and a thin multilayer A multilayer silicon semiconductor wafer characterized by having a gettering ability even in a structure.   The multilayer silicon semiconductor wafer according to claim 1, wherein the damaged layer is formed by sandblasting, mechanical grinding, or by leaving polishing scratches or damage on the back surface by laser irradiation.   A semiconductor device comprising the multilayer silicon semiconductor wafer according to claim 1.   Polishing the back surface of the silicon semiconductor wafer on which the device has been formed, thinning it, forming a damaged layer on the back polished surface of the thinned silicon semiconductor wafer, and manufacturing the individual silicon semiconductor wafer; and forming the device And laminating a plurality of individual silicon semiconductor wafers having a damaged layer formed on the back surface thereof, each of the laminated layers having an individual device and a damaged layer, and a thin multilayer structure Even so, a method for producing a multilayer silicon semiconductor wafer comprising producing a multilayer silicon semiconductor wafer having gettering ability.   5. The method according to claim 4, wherein the damaged layer is formed by sandblasting, mechanical grinding, or by leaving polishing scratches or damage on the back surface by laser irradiation.   6. The method according to claim 4, wherein the multilayer silicon semiconductor wafer is a semiconductor device.

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