JPH01251620A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To enable a semiconductor to be worked into desired configurations reliably, by forming a high-concentration diffused layer on the surface of a substrate on which electric elements are to be formed such that the diffused layer reaches at least proximity of a region to be shaped by electrochemical etching, and applying a bias voltage through the high-concentration diffused layer. CONSTITUTION:A scribed region with an appropriate width is provided around each semiconductor chip on the side of an n-type semiconductor layer on which electric elements are to be formed. N<+> diffused layers 2 with high concentration or N<+> interconnections 3 are formed in these regions by ion implantation or by diffusion, and then a protective layer of SiO2 for example is formed on the surface thereof. The N<+> interconnections 3 have functions of helping to apply equal voltage to all the semiconductor chips 1 as well as of decreasing contact resistance generated when they are electrically connected to the outside. The N<+> interconnections 3 are then connected to a power supply and a structure to be produced by etching an N-type semiconductor layer is set at a positive potential through the N<+> interconnections 3 such that the surface thereof is anodically oxidized to produce SiO2.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for manufacturing a semiconductor device, and particularly to a method for manufacturing a semiconductor device in which shape processing is performed by electrochemical etching.

[Conventional technology]

Examples of this type of semiconductor device whose shape is processed by electrochemical etching include micromechanical devices such as semiconductor pressure sensors and semiconductor acceleration sensors. A major feature of these devices is that they not only simply form electrical elements on a semiconductor substrate, but also process the semiconductor substrate into fine structures such as thin film diaphragms and cantilevers. Electrochemical etching is used as a high-precision processing method for the microstructure.

The conventional electrochemical etching method will be explained below.

In the manufacture of semiconductor devices using the electrochemical etching method, an n/ρ epiwafer in which an n-type semiconductor layer is laminated on one side of a p-type semiconductor substrate by an epitaxial growth method or the like, or a substrate in which a p-n junction is formed by a diffusion method is used. , the substrate is immersed in an etching solution with the n-type semiconductor portion biased to a positive voltage. At this time, the positive voltage applied to the n-type semiconductor portion is set to such a level that a silicon oxide film is generated by the anodic oxidation reaction in the etching solution, and the etching is carried out from the p-type semiconductor surface to the n-type semiconductor. When the etching reaches the semiconductor, an oxide film is formed near the pn junction interface, so etching stops at the pn junction interface.

As described above, in electrochemical etching, it is necessary to supply voltage to the semiconductor substrate from the outside by some method. FIG. 2 shows a schematic diagram of a semiconductor substrate that has been used in conventional electrochemical etching. As shown in the figure, conventionally, a high concentration diffusion region made of an n+ diffusion layer 12 is provided in a circular shape so as to surround the peripheral portion of the surface of a semiconductor wafer 11, and an n-type semiconductor portion 13 is formed through the high concentration diffusion region. The desired voltage and current were supplied externally.

[Problem to be solved by the invention]

Incidentally, the formation of a silicon oxide film in an etching solution is controlled by the potential applied to the semiconductor. However, in the structure of the conventional semiconductor substrate shown in FIG. 2, the electrical resistance of the silicon portion other than the peripheral portion is considerably higher than that of the peripheral portion.

As you go from the periphery to the center, the voltage on the substrate becomes different from the voltage supplied from the outside. Furthermore, as the silicon film thickness decreases as etching progresses, the resistance value of the silicon parts other than the peripheral part increases to an even larger value, and the difference between the voltage value set by the external power supply and the voltage value at each chip part increases. It becomes even more noticeable. As a result, an oxide film begins to form in the central part before the etching reaches the p-n junction interface, and the p-type silicon part that should have been etched remains unetched, making it impossible to process the exact shape. There was a serious problem.

An object of the present invention is to provide a method for manufacturing a semiconductor device that completely overcomes the problems of the prior art described above and can reliably process a desired semiconductor shape.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a method for manufacturing a semiconductor device in which an electrical element is formed on a semiconductor substrate and the semiconductor substrate is processed into a desired shape by an electrochemical etching method. A high concentration diffusion layer is formed on the substrate surface on the side to be etched, so as to reach at least the vicinity of the region to be shaped by the electrochemical etching.

A bias voltage for electrochemical etching is supplied through the high concentration diffusion layer.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method for manufacturing a semiconductor device according to the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram showing an example of the structure of a semiconductor substrate used in an embodiment of the present invention. As shown in the figure, a scribe region of an appropriate width is provided around each semiconductor chip 1 on the n-type semiconductor layer side where electrical elements are formed, and a high concentration of 000 After forming the diffusion layer 2, that is, the N" wiring 3, 5i0 is applied to the surface.
A protective layer such as 1 is provided. This N3 wiring 3 has the function of applying voltage to each semiconductor chip 1 under the same conditions,
external.

It has the function of reducing contact resistance that occurs during any electrical connection. After that, connect this N0 wiring 3 to the power supply,
Anodic oxidation occurs on the surface of the structure made of an n-type semiconductor layer to be fabricated by etching, and Si
While setting the potential through the N9 wiring 3 to a positive potential that generates O KO) l series,
Then, it is immersed in a solution capable of silicon anisotropic etching, such as hydrazine, and etched by heating it to around 90 degrees.

According to this embodiment, the N3 wiring 3 is applied over the entire surface of the wafer so that the applied voltage is uniformly applied to any part of the structure made of the n-type semiconductor layer to be fabricated by etching.
is formed, the shape processing by etching is performed uniformly on all parts, making it possible to obtain high processing accuracy and high yield.

In the semiconductor substrate of the above embodiment shown in FIG. 1, an N+ conductor layer is also provided in the periphery other than the scribe area, but as long as a region that can be connected to an external power source is provided, the peripheral conductor layer can be You can do without it. In that case,
Chips can now be placed in the area that was previously spent forming N'''' layers on the periphery, further improving the yield per wafer.

〔Effect of the invention〕

As explained above, according to the present invention, the N4 wiring is formed over the entire surface of the semiconductor substrate so that an applied voltage can be uniformly applied to any part of the structure made of one conductivity type semiconductor layer to be fabricated by electrochemical etching. Therefore, shape processing by electrochemical etching is uniformly performed on all parts, and high processing accuracy and high yield can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a front view showing an example of a semiconductor substrate used for electrochemical etching in an embodiment of the present invention, and FIG. 2 is a front view of a semiconductor substrate used for conventional electrochemical etching.

Claims (1)

[Claims] 1. In a method for manufacturing a semiconductor device in which an electrical element is formed on a semiconductor substrate and the semiconductor substrate is processed into a desired shape by electrochemical etching, the above-mentioned A semiconductor device characterized by forming a highly concentrated diffusion layer that reaches at least the vicinity of a region to be shaped by electrochemical etching, and supplying a bias voltage for electrochemical etching through the highly concentrated diffusion layer. manufacturing method.