RU2437181C1 - Manufacturing method of deep-shaped silicon structures - Google Patents

Abstract

FIELD: instrument making.

SUBSTANCE: manufacturing method of deep-shaped silicon structures involves creation of protective layer on silicon plate; formation in it by means of in-series photolithography and etching operations the structure of the specified shape till silicon appears in the area of its maximum depth, and then silicon and the rest protective layer is etched till the specified shape is obtained. According to the invention, after creation of protective layer and prior to the first photolithography operation, along the protective layer surface there created is contrast layer from the material differing from protective layer material, and after each photolithography operation prior to etching of protective layer there etched is contrast layer.

EFFECT: improving manufacturing accuracy of deep-shaped silicon structures.

10 dwg

Description

The invention relates to instrumentation and can be used in the manufacture of semiconductor micromechanical devices, for example, sensitive elements of integrated sensors.

A known method of manufacturing deeply profiled silicon structures [1], which consists in the fact that a photoresist is applied to the protective layer of the silicon wafer, a contour in the photoresist is formed using photolithography, the protective layer in the photoresist contour is removed until silicon appears, the silicon is etched to the desired depth, and then produced repeated operations until a predetermined profile is formed in silicon.

The disadvantages of this method are:

- uneven deposition of a photoresist film on the resulting embossed surface;

- tears of the photoresist film on the sharp edges of the etched surface;

- large thickness in etched grooves.

This leads to the great complexity of the operation of photolithography and to a large number of defects.

The prototype of the proposed technical solution is the method [2], in which the structure of a given profile is formed in the protective layer using sequential photolithography and etching operations, and the specified profile is created in silicon by alternating the etching operations of the protective layer and silicon.

The disadvantage of this method is the complexity and inaccuracy of combining photo masks with the 2nd and subsequent photolithography operations relative to the contour formed after the 1st photolithography. Difficulties in combining photo masks arise due to insufficient visibility of the contour through the applied photoresist.

The objective of the invention is to increase the accuracy of manufacturing deeply profiled silicon structures.

The problem is solved due to the fact that in the method of manufacturing deeply profiled silicon structures, which consists in creating a protective layer on a silicon wafer, forming in it successive operations of photolithography and etching the structure of a given profile until silicon appears in the region of the maximum depth of the structure and subsequent alternating etching of silicon and the remaining a protective layer until a predetermined profile is obtained in silicon according to the invention after creating a protective layer and before the first operation otolitografii on the surface of the protective layer provide the contrast layer of a material different from the material of the protective layer, and after each operation photolithography etching to etch away the protective layer of the contrast layer.

A significant difference between the proposed method and the known one is the creation of a contrast layer from a material that is different from the material of the protective layer, as a result of which the formed contour in the protective layer after the 1st photolithography is clearly visible against the background of the contrast layer, which increases the accuracy of creating deeply profiled silicon structures by reducing the error combining photo masks.

In the drawings, Figures 1-10 show the sequence of operations used to implement the proposed method. A protective layer 2 is created on the silicon wafer 1, on which a contrast layer 3 is located. A photoresist 4 is deposited on top of the contrast layer 3, in which windows 5 are formed and a structure 6 of a given profile 7 is formed.

An example implementation of the proposed method is described below.

On the silicon wafer 1 create a protective layer 2, for example, from a film of silicon oxide with a thickness of 2 μm (figure 1). A contrast layer 3 is applied to the protective layer 2, for example, from an aluminum film 1 μm thick (FIG. 2). A photolithography operation is carried out, which consists in applying photoresist 4 to a contrast layer 3 (Fig. 3), exposing through a photo mask, developing and heat treating photoresist 4. Fig. 4 shows formed windows 5 in photoresist 4 after its development. In places of the formed windows 5, the contrast layer 3 is etched until the protective layer 2 appears (Fig. 5). Then, the protective layer 2 is etched to the desired depth (Fig. 6) and the remaining photoresist film 4 is removed from the entire wafer 1. By subsequent photolithography and etching, a predetermined profile structure 6 is formed in the protective layer 2 of the silicon wafer 1 (Fig. 7) until silicon appears in the maximum depth of the structure 6 of a given profile, after which the photoresist 4 is washed off and the contrast layer 3 is removed (Fig. 8). In etchants that do not react or react poorly with the protective layer 2, silicon is etched to the desired depth (Fig. 9). Then, alternating the etching of the protective layer 2 until the next circuit is opened and the etching of silicon, the desired profile 7 in silicon is obtained, after which the entire protective layer 2 is removed from the silicon wafer 1 (Fig. 10).

As a result of the application of the proposed method, the manufacturing accuracy of deeply profiled silicon structures has increased.

Information sources

1. Press F.P. Photolithographic methods in the technology of semiconductor devices and integrated circuits. - M .: Soviet Radio, 1978, p. 78, 79.

2. Copyright certificate of the USSR 1228720, cl. H01L 21/306, publ. 1995 (prototype).

Claims (1)

A method of manufacturing deeply profiled silicon structures, which consists in creating a protective layer on a silicon wafer, forming in it successive operations of photolithography and etching the structure of a given profile until silicon appears in the region of the maximum depth of the structure and then alternating the etching of silicon and the remaining protective layer until a specified profile is obtained in silicon, characterized in that after the creation of the protective layer and before the first photolithography operation on the surface of the protective layer ayut contrast layer of a material different from the material of the protective layer, and after each operation photolithography etching to etch away the protective layer of the contrast layer.

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