JPH04342116A - Manufacture of epitaxial growth wafer - Google Patents

Abstract

PURPOSE:To eliminate that an epitaxial layer is stripped during a wafer process and to enhance the yield of a silicon wafer by a method wherein the outer circumferential face of the silicon wafer is exposed and the epitaxial layer having a sufficient thickness is formed also on the outer circumferential face in the same manner as on the face of the wafer. CONSTITUTION:A polysilicon film 12 is formed on the whole face of a silicon wafer 11; then, the polysilicon film 12 on the outer circumferential face of the silicon wafer 11 is removed; the polysilicon film 12 on the face, on one side, of the silicon wafer 11 is removed; after that, an epitaxial layer 14 is formed on the face, on one side, and the outer circumferential face of the silicon wafer 11 from which the polysilicon film has been removed.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing epitaxially grown wafers.

0002

[Prior Art] Usually, CCD (Charged Co
Epitaxially grown wafers used for (upled devices) need to prevent white spot defects, which are one of the image defects. For this reason, strong gettering, such as extrinsic gettering (hereinafter abbreviated as EG), is performed on the wafer on which the CCD is formed.

Next, a method for manufacturing an epitaxially grown wafer in which EG is performed using a polysilicon film will be explained with reference to the flowchart shown in FIG. As shown in the figure, the silicon wafer 21 is an etched wafer obtained by cleaning a single crystal silicon wafer by etching or the like. Then, the entire surface of the cleaned silicon wafer 21 (wafer surface 2
1a, 21b and the outer peripheral surface 21c), a polysilicon film 22 for performing EG is formed. Next, a silicon oxide film 2 is formed on the entire surface of the polysilicon film 22 by chemical vapor deposition.
Cover 3. By covering this silicon oxide film 23, the polysilicon film 22 and a susceptor (not shown) coated with a polysilicon film of an epitaxial growth apparatus react with the grown epitaxial layer (24) and adhere to each other during epitaxial growth to be described later. prevent

[0004] After that, the silicon oxide film 23 (double-dashed line) and the polysilicon film 22 (dotted-dash line) are removed by, for example, polishing (lapping, polishing), and one side of the silicon wafer 21 is exposed. do. The exposed surface of the silicon wafer 21 becomes a smooth mirror surface. Next, an epitaxial layer 24 is formed on the exposed surface of the silicon wafer 21 by an epitaxial growth method. This epitaxial layer 24 is made of single crystal silicon. silicon wafer 2
A polysilicon layer 25 is formed on the surface of the silicon oxide film 23 in the outer peripheral portion of the silicon oxide film 23 during this epitaxial growth. As described above, the epitaxially grown wafer 20
is completed.

[0005]

However, when a front-end wafer process is performed using an epitaxially grown wafer manufactured by the conventional technique, the following problems occur. As shown in FIG. 3, when hydrofluoric acid etching is performed in the pre-wafer process, the surface layer of the silicon oxide film 23 is etched and removed. For this reason,
The polysilicon layer 25 covering the silicon oxide film 23 is peeled off. The peeled epitaxial layer 25 becomes foreign matter and re-adheres to the surface of the epitaxial layer 24. For this reason, when, for example, a photolithography process is performed after etching in the pre-process, the attached foreign matter acts as a mask and causes pattern defects. Furthermore, for example, poor coverage occurs in a film forming process. Therefore, the yield of the front-end process decreases.

An object of the present invention is to provide a method for manufacturing epitaxially grown wafers that does not generate foreign matter.

[0007]

[Means for Solving the Problems] The present invention has been made to achieve the above objects. That is, a polysilicon film is formed over the entire surface of a silicon wafer. Thereafter, the polysilicon film on the outer peripheral surface of the silicon wafer is removed, and the polysilicon film on one side of the silicon wafer is removed. Next, an epitaxial layer is formed on one side of the silicon wafer from which the polysilicon film has been removed and on the same outer peripheral surface.

[0008]

[Operation] In the method for manufacturing an epitaxially grown wafer described above, before forming an epitaxial layer, the polysilicon film on the outer peripheral surface of the silicon wafer is removed to expose the outer peripheral surface of the silicon wafer. Therefore, by epitaxial growth, an epitaxial layer of the same quality and substantially sufficient thickness is formed on one side of the silicon wafer and the same outer peripheral surface. As a result, the epitaxial layer becomes difficult to peel off.

[0009]

EXAMPLE An example of the present invention will be explained with reference to the flowchart shown in FIG. As shown in the figure, epitaxial growth wafer 1
To manufacture the silicon wafer 11, first, the entire surface of the silicon wafer 11 (wafer surfaces 11a, 11b and outer peripheral surface 11c) is cleaned by etching or the like. Next, a polysilicon film 12 is formed on the entire surface of the cleaned silicon wafer 11 by, for example, chemical vapor deposition. Subsequently, a silicon oxide film 13 is formed over the entire surface of the polysilicon film 12 by, for example, chemical vapor deposition. Note that if polysilicon 12 and a susceptor (not shown) of an epitaxial growth apparatus do not adhere to each other during epitaxial growth to be described later, it is not necessary to form silicon oxide film 13.

[0010] Thereafter, the process proceeds to the step shown in the direction of arrow A, for example. In this step, for example, the outer peripheral surface 11c of the silicon wafer is
By grinding and chamfering the outer periphery of the wafer, the polysilicon film 12 (dotted chain line) and silicon oxide film 13 (
The two-dot chain line portion) is removed. At this time, in order to sufficiently remove the polysilicon film 12, the outer peripheral surface 11c (dashed line portion) of the silicon wafer 11 is also ground. Thereafter, cleaning is performed using a cleaning liquid such as ammonia-hydrogen to remove grinding debris that has adhered to the surface of the polysilicon film 12 due to peripheral grinding. Subsequently, the silicon oxide film 13 and the polysilicon film 1 on the wafer surface 11a on one side of the silicon wafer 11 are
2 is removed by, for example, polishing. Usually, in this polishing, after lapping is performed, the damaged layer caused by the lapping is removed by etching. The surface is then polished to a flat, mirror-like finish.

Next, an epitaxial layer 14 is formed on one wafer surface 11a and the outer peripheral surface 11c of the exposed silicon wafer 11 by an epitaxial growth method. Since this epitaxial layer 14 is grown from the silicon wafer 11 made of single crystal silicon, it becomes a single crystal silicon layer. The epitaxially grown wafer 1 is then completed.

Alternatively, after forming the polysilicon film 12 and the silicon oxide film 13 on the silicon wafer 11, the process proceeds to the step shown in the direction of arrow B. In this step, the silicon oxide film 13 and polysilicon film 12 on the wafer surface 11c on one side of the silicon wafer 11 are removed, for example, by polishing. Next, by normal wafer peripheral grinding,
Polysilicon film 12 (double-dashed line) and silicon oxide film 13 (dotted-dash line) on outer peripheral surface 11c of silicon wafer 11 are removed. At this time, polysilicon film 1
2, the outer circumferential surface 11c (dashed line portion) of the silicon wafer 11 is also ground. Subsequently, using a cleaning solution such as ammonia peroxide, the grinding debris adhering to the surface of the polysilicon film 12 and the polished surface of the wafer are removed. It is also possible to form the epitaxial growth wafer 1 by subsequently performing the epitaxial growth described above.

[0013]

[Effects of the Invention] As explained above, according to the present invention,
Since the polysilicon film was removed to expose one side and the outer peripheral surface of the silicon wafer, an epitaxial layer of the same quality and sufficient thickness was formed on the exposed one side and the outer peripheral surface. Ru. Therefore, the epitaxial layer on the outer peripheral surface of the silicon wafer will not peel off even if the pre-process is performed. Therefore, the yield of the front-end process can be improved.

[Brief explanation of drawings]

FIG. 1 is a flowchart of a manufacturing method of an example.

FIG. 2 is a flowchart of a conventional manufacturing method.

FIG. 3 is an explanatory diagram of a problem.

[Explanation of symbols]

1 Epitaxial growth wafer 11 Silicon wafer 12 Polysilicon film 14 Epitaxial layer

Claims (1)

[Claims] 1. A step of forming a polysilicon film on the entire surface of a silicon wafer, removing the polysilicon film on the outer peripheral surface of the silicon wafer, and removing the polysilicon film on one side of the silicon wafer. A method for producing an epitaxially grown wafer, comprising sequentially performing a step of forming an epitaxial layer on one side of the silicon wafer from which the polysilicon film has been removed, and forming an epitaxial layer on the outer peripheral surface of the silicon wafer.