JP2008166576A - Semiconductor device manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method that allows manufacturing of a semiconductor device employing a thin silicon wafer without edge chipping on the silicon wafer. <P>SOLUTION: The back 4 of the wafer W is formed with a recess portion 5 having a shape in which an overall part included in the center 1 of the back 4 is recessed towards the surface side. Afterwards, an etching fluid is supplied to the surface 3 and the back 4 of the wafer W, and the surface 3 and the back 4 of the wafer W are etched. This etching allows the edge portions 2 of the wafer W to have a thickness larger than the thickness of the center thereof 1 by the depth of the recessed portion 5 when the center 1 of the wafer the wafer W is thinned to a desired thickness. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a semiconductor device using a silicon wafer.

Recently, since the mounting of a sensor (MEMS sensor) using MEMS (Micro Electro Mechanical Systems) technology on a mobile phone has been started, the attention of the MEMS sensor is increasing. As a typical MEMS sensor, an acceleration sensor and a silicon microphone for detecting the acceleration of an object are known.
The manufacturing process of the MEMS sensor includes a process of thinning the silicon wafer (wafer thinning process). Thinning of the silicon wafer can be achieved by grinding and / or etching the silicon wafer from its back side (opposite to the surface on which the device is formed). Currently, silicon wafers used in MEMS sensors are thinned to a thickness of about 200 to 400 μm in the wafer thinning process.
JP 2005-161516 A

  As shown in FIG. 2, in the silicon wafer, the cross-sectional shape of the edge portion is an R shape (convex curved shape). Therefore, when the silicon wafer is thinned to ½ or more of the original thickness, the cross-sectional shape of the edge portion becomes sharp, and the mechanical strength of the edge portion becomes very weak. As a result, when handling the silicon wafer, the edge portion of the silicon wafer may be damaged, so-called edge chipping may occur.

  Accordingly, an object of the present invention is to provide a method capable of manufacturing a semiconductor device using a thinned silicon wafer without causing edge chipping of the silicon wafer.

  In order to achieve the above object, according to the first aspect of the present invention, a recess is formed in the center of the back surface opposite to the surface on which the device of the silicon wafer is formed, and the center of the silicon wafer is thinned. 1 wafer thinning step and after the first wafer thinning step, a second wafer thinning step in which the front and back surfaces of the silicon wafer are etched to thin the center portion of the silicon wafer and the peripheral edge portion thereof. A method for manufacturing a semiconductor device.

In a silicon wafer, the central portion is a region used for manufacturing a semiconductor device (device forming region where a device is formed), and an edge portion (peripheral portion) around the central portion is used for manufacturing a semiconductor device. No region (non-device formation region where no device is formed).
In the above manufacturing method, the central portion of the silicon wafer is thinned by forming the concave portion in the central portion of the back surface of the silicon wafer (the portion included in the device formation region on the back surface of the silicon wafer). Thereafter, the center and edge portions of the silicon wafer are thinned by etching the front and back surfaces of the silicon wafer. This etching proceeds at the same rate at the center and edge portions of the front surface and back surface of the silicon wafer. Therefore, when the central portion of the silicon wafer is thinned to a desired thickness, the edge portion of the silicon wafer has a thickness larger than the thickness of the central portion by the depth of the concave portion. As a result, the mechanical strength of the edge portion of the silicon wafer can be ensured, so that edge chipping of the silicon wafer can be prevented. Therefore, a semiconductor device using the thinned silicon wafer can be manufactured without causing edge chipping of the silicon wafer.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a schematic view for explaining a method for manufacturing a semiconductor device according to an embodiment of the present invention.
In this method of manufacturing a semiconductor device, first, as shown in FIG. 1A, a silicon wafer (hereinafter simply referred to as “wafer”) W is prepared. In the wafer W, the central portion 1 is a region used for manufacturing a semiconductor device, and an edge portion 2 around the central portion 1 is a region not used for manufacturing a semiconductor device. Then, in the central portion 1 of the wafer W, a device such as a transistor is formed on the surface layer portion on the surface 3 side.

  Next, as shown in FIG. 1B, a concave portion having a shape in which a portion included in the central portion 1 of the back surface 4 is entirely recessed on the front surface side on the back surface 4 opposite to the front surface 3 of the wafer W. 5 is formed. Thereby, the central portion 1 of the wafer W is thinned to a thickness (400 μm) that is about two-thirds of the original thickness (625 μm), for example (first wafer thinning step). The concave portion 5 may be formed by grinding or may be formed by etching.

  Thereafter, an etchant is supplied to the front surface 3 and the back surface 4 of the wafer W, and the front surface 3 and the back surface 4 of the wafer W are etched (second wafer thinning step). This etching proceeds at the same rate on the front surface 3 and the rear surface 4 (including the inside of the recess 5) of the wafer W. Therefore, as shown in FIG. 1C, when the central portion 1 of the wafer W is thinned to a desired thickness (for example, 300 μm), the edge portion 2 of the wafer W has a thickness of the central portion 1. It has a thickness larger than the thickness by the depth of the recess 5.

  In this way, by leaving a relatively large thickness at the edge portion 2 of the wafer W, the mechanical strength of the edge portion 2 of the wafer W can be ensured, so that the occurrence of edge chipping of the wafer W can be prevented. Can do. Therefore, a semiconductor device including a MEMS sensor or the like can be manufactured using the thinned wafer W without causing edge chipping when the wafer W is handled.

  Although one embodiment of the present invention has been described above, various design changes can be made to this embodiment within the scope of the matters described in the claims.

It is a typical figure for explaining a manufacturing method of a semiconductor device concerning one embodiment of the present invention. It is a typical side view which shows the shape of the edge part of the conventional thinned silicon wafer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Center part 2 Edge part 3 Front surface 4 Back surface 5 Recessed part W Wafer

Claims (1)

A first wafer thinning step of forming a recess in the center of the back surface opposite to the surface on which the device of the silicon wafer is formed, and thinning the center of the silicon wafer;
A second wafer thinning step including etching a front surface and a back surface of the silicon wafer after the first wafer thinning step to thin a central portion of the silicon wafer and a peripheral edge portion thereof. Production method.

Images