JPH01251619A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To enable etching of silicon to be carried out reliability, by providing a low-resistance layer such that it reaches at least proximity of a structure to be formed on the surface of a substrate opposite to that on which the principal electronic circuit is formed, and connecting the low-resistance layer with electrodes used for electrochemical etching. CONSTITUTION:A low-resistance circuit is provided on the opposite sides of a substrate 2. A scribed region having a width of about 1mm is formed around each chip of principal circuit sections 2 and 3. By diffusion, P<+> interconnections 4 are formed on a P-type semiconductor layer on the top face and N<+> interconnections 5 are formed on an N-type semiconductor layer on the rear face. Thereafter, a protecting layer of SiO2 for example is provided on the surface of the substrate 1. Formation of the conducting paths helps uniform application of voltage to all the semiconductor chips and dramatically decreases contact resistance produced when the electric circuit is connected to the outside. The N<+> interconnections 5 are then connected to a constant-voltage power supply provided externally and a structure to be formed by etching the N-type semiconductor layer is set at a positive potential 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 of manufacturing a semiconductor device.

[Conventional technology]

In recent years, among methods for processing semiconductor devices, etching methods using electrochemical phenomena have been attracting attention.

The technology usually involves first depositing on one side of a P-type semiconductor substrate.
A substrate having a structure in which an N-type semiconductor layer is provided and a PN junction is formed using a diffusion method, an epitaxy growth method, or the like is prepared. Next, a positive voltage is applied to the N-type semiconductor in an etching solution to the extent that a silicon oxide film is formed on it by an anodic oxidation reaction4, and when the etching reaches the N-type semiconductor from the P-type semiconductor surface, the This is done by forming an oxide film near the PN junction interface and stopping etching at that interface. However, this requires an external voltage supply. FIG. 2 shows a conventionally used substrate. In the figure, conventionally,
A circular high-concentration diffusion region 1 is formed around the periphery of one side of the semiconductor wafer 11 where the main circuit portion 12 is provided.
3. In other words, by providing a low-resistance layer, we can maintain continuity while keeping the contact resistance with external wiring low.
It was devised so that the desired voltage and current could be supplied from outside using a constant voltage power supply.

[Problem to be solved by the invention]

By the way, the formation of a silicon oxide film in an etching solution is controlled by the potential applied to the semiconductor, so in the structure described above, the electrical resistance of the silicon portion other than the circumferential portion is considerably lower than that of the circumferential portion. Because of this, the voltage becomes different from the voltage supplied from the outside as you move from the circumference to the center, and as the silicon film thickness decreases as etching progresses, the resistance value becomes even higher. As the value increases, the difference between the set voltage value by the external power supply and the voltage value at each chip portion becomes significant, and before the etching reaches the PN junction interface, an oxide layer begins to form in the central portion, which would otherwise be etched. There was a serious problem in that a portion of the silicon that should be etched remained unetched, making it impossible to perform accurate etching.

An object of the present invention is to provide a method that completely overcomes the above-mentioned conventional problems and can reliably perform silicon etching.

[Means to solve the problem]

In order to achieve the above object, in the method of manufacturing a semiconductor device of the present invention, in a method of manufacturing a semiconductor device using electrochemical etching, etching is applied to both sides of the substrate up to at least the vicinity of the structure to be formed separately from the main electronic circuit. Provide a resistance layer,
The low resistance layer is connected to an electrode for electrochemical etching.

[Effect]

The electrochemical etching method of the present invention involves forming low resistance circuits on both sides of the substrate to supply the voltage and current required for electrochemical etching to parts other than the main circuit forming part, and connecting these to an external power supply. This makes it possible to precisely control the potential of the portion to be removed by electrochemical etching. This ensures that the etching is complete and that any shape required can be etched.

〔Example〕

BRIEF DESCRIPTION OF THE DRAWINGS One & preferred embodiment of the method according to the invention will be explained on the basis of the following drawings.

FIGS. 1(a) and 1(b) respectively show the surface of the substrate 1,
The back side is shown. 2 is a main circuit portion on the front side, and 3 is a main circuit portion on the back side. A scribe area of approximately 1 mm is provided around each chip in the main circuit section, and ion implantation or diffusion is applied thereto to form a P+ wiring 4 on the P-type semiconductor layer surface on the front surface, and an N
An N+ wiring 5 is formed on the surface of the type semiconductor layer. After that, a protective layer such as 5if2 is provided on the surface. The formation of this conductive path has the function of promoting the application of voltage to each semiconductor chip in the same way, and the function of drastically reducing the contact resistance that occurs when connecting an external electrical circuit. After that, it is connected to an external constant voltage power supply, and the structure to be fabricated by etching consisting of the N-type semiconductor layer is heated to a positive potential to the extent that anodic oxidation occurs on the surface and 5t02 is generated. On the other hand, when no voltage is applied from the outside to the P-type semiconductor layer portion cut out by etching to the silicon substrate, the anisotropic etching of St ill! The P+ wiring 4 is connected so that it is on the negative side of the natural equilibrium potential that occurs subsequently.
Etching is performed by immersing silicon in a solution capable of anisotropic etching such as ethylenediamine, KOH, or hydrazine, and heating it to around 90 degrees.0 Etching is usually performed from the P-type semiconductor layer. However, when metals such as aluminum are used as wiring wires, they are side-etched during anisotropic etching and lose their function as conductors, and the melted metals contaminate the etching solution and cause etching problems. Significantly shortens the life of the liquid.

However, when the diffusion layer is used as a conductive layer, the surface becomes 3i02
It is possible to overcome the above drawbacks by protecting the In addition, when a conductor layer is provided in this way, the effective manufacturing area of the chip is extremely reduced because in the conventional method, about 1 cm of the outer circumference of the circular silicon wafer is used to form the N+ layer. However, it is possible to improve it significantly.

In the figure, a conductor layer is also provided around the area other than the scribe area, but that part may be omitted as long as a place that can be connected to an external power source is provided.

〔Effect of the invention〕

As explained above, according to the present invention, the voltage applied from the outside can be controlled so as to be uniformly applied to any part of the silicon wafer, so that thin films can be formed by etching in very fine shapes. However, all parts are extremely good, and all chips can be used as products.

[Brief explanation of the drawing]

FIG. 1(a) is a plan view of a semiconductor substrate used for electrochemical etching according to the present invention, FIG. 1(b) is a bottom view, and FIG. 2 is a plan view of a semiconductor substrate conventionally used for electrochemical etching. 1... Board 2... Main circuit part 3...
・Main circuit part 4...P+ wiring 5...N+ wiring Patent applicant NEC Corporation Agent Patent attorney Susumu Uchihara (α(b)) Figure 1

Claims (1)

[Claims] 1. In a method of manufacturing a semiconductor device using electrochemical etching, a low resistance layer is provided on both sides of the substrate up to at least the vicinity of the structure to be formed separately from the main electronic circuit, and the low resistance layer is used for electrochemical etching. A method for manufacturing a semiconductor device, characterized in that it is connected to an electrode.