KR940005704B1 - Method of making silicon thin film - Google Patents

Abstract

The method is for manufacturing silicon thin film using a silicon direct bonding technology. The method comprises the steps of: (a) bonding a silicon layer (1) and a silicon oxide layer (5); (b) etching a silicon oxide layer; (c) vaporizing netrogenized silicon (Si3N4); (d) removing etching protect layer (6) and etching a silicon substrate (2); and (e) polishing the silicon layer (1).

Description

Silicon thin film manufacturing method using silicon substrate direct bonding method

(A)-(h) is sectional drawing which shows the manufacturing method of the silicon thin film which has a cross-sectional board support.

(A)-(g) is sectional drawing which showed the silicon thin film manufacturing method which has a double-sided substrate support.

(A)-(i) of FIG. 3 is sectional drawing which shows the manufacturing method of the silicon thin film which has a thin film support.

(A)-(b) is sectional drawing which shows one Example of the mask for X-rays with a thin film support.

5 is a cross-sectional view showing the production of a substrate thin film such as a silicon oxide film or a silicon nitride film.

* Explanation of symbols for main parts of the drawings

2, 3, 12, 13, 22, 23, 41, 44: silicon substrate

6a, 6b, 14, 27, 27a, 46a, 46b: surface protective film

1, 4, 11, 21, 42, 45: silicon layer 5, 26: silicon oxide film

The present invention relates to a silicon thin film manufacturing method using a silicon substrate direct bonding method,

Conventional methods of manufacturing a silicon thin film include a selective substrate etching method using a difference in concentration of impurities in a silicon substrate, and a method of manufacturing a silicon thin film by bonding a silicon substrate using wax on a glass substrate and then performing a polishing operation.

In this way, it is difficult to manufacture a very thin film having a large area, and uniformity cannot be improved to a certain level or more. Accordingly, the present invention provides a method for producing a silicon thin film using a silicon substrate direct bonding method for producing a wide-area silicon thin film by using two silicon substrates using a silicon substrate direct bonding method and to improve uniformity. The purpose.

Next, the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows a method for manufacturing a silicon thin film of a single-sided substrate support, in which a silicon layer 1 containing low concentration impurities is grown on a silicon substrate 2 by an epitaxial growth method (FIG. 1 (a)). At this time, the growth thickness is about 0.5 to several tens of the thickness of the final desired silicon thin film, and should be considered the polishing thickness after external diffusion and selective etching occurring in the silicon substrate containing high concentration impurities during the adhesive heat treatment. A silicon layer 4 containing low concentration impurities is grown on the silicon substrate 3 containing high concentration impurities, and the surface layer is oxidized to form a silicon oxide film 5 ((b) of FIG. 1).

The silicon layer 4 including the low concentration impurity is used as an etch barrier layer during backside etching.

Then, the two substrates are bonded to each other with the silicon layer 1 and the silicon oxide film layer 5 facing each other ((c) in FIG. 1). At this time, the method of bonding two substrates is silicon silicon direct contact _{2 4 2 2 2}

Subsequently, the substrate is immersed in the cleaning solution to adsorb OH groups on the surface of the substrate. Then, the two silicon substrates on which OH groups are adsorbed are attached to each other at room temperature, and then subjected to a heat treatment at 1000 ° C. in a crucible for 1 hour. A silicon nitride film (Si ₃ N ₄ ) 6 is deposited on both surfaces of the bonded substrate as an etch protective film. Then, the etching protection film 6 of the silicon substrate 2 to be selectively etched is removed ((d) of FIG. 1). Subsequently, the substrate is immersed in an etching solution (HF: HNO ₃ : CH ₃ COOH = 1: 3: 8) to selectively remove the silicon substrate 2 containing high concentration impurities ((e) of FIG. 1).

After removing the etch protective film 6 by using a phosphoric acid solution (H ₃ PO ₄ ), the silicon layer 1 containing low concentration impurities is polished to improve the uniformity of the thin film.

After the surface polishing is finished, the etching protective film 6b is deposited again, and then the etching protective film 6a of the portion to be thinned is removed to etch the silicon substrate 3 ((f) of FIG. 1).

Then, after the photosensitive film is coated on the back surface of the substrate to define the shape, the light is applied to a portion to be removed using a light source, and then the photosensitive film is removed using a developer. After removing the etch protection layer of the portion where the photoresist film is removed, the photoresist film may be removed.

The back side etching is performed using an etching solution (HF: HNO ₃ : CH ₃ COOH = 1: 3: 8) to etch the silicon substrate (3) containing a high concentration of impurities (Fig. 1 (g)).

After the etching protective film 6a is removed, the silicon layer 4 containing the low concentration impurity used as the etching blocking film is subjected to dry etching (RIE etch, etc.), and then the silicon oxide film insects 5 are removed ((h of FIG. )).

The silicon layer 1 of (h) of FIG. 1 is a silicon layer containing the low concentration impurity which forms the silicon thin film layer, and the silicon substrate 3 is the silicon layer containing the high concentration impurity which remained by the board | substrate support. 2 is a view illustrating a process of manufacturing a silicon thin film having a double-sided substrate support, in which a silicon layer 11 containing a low concentration of impurities is grown on a silicon substrate 12 containing a high concentration of impurities by an epitaxial method (see FIG. a)). The silicon substrate 13 is shown (FIG. 12 (b)). The silicon layer 11 and the silicon substrate 13 are attached by the silicon substrate direct bonding method ((c) of FIG. 2). A silicon nitride film (Si ₃ N ₄ ) 14 is deposited on the surface to which the two sheets 11 and 13 are adhered by an etch protective film ((d) of FIG. 2). The silicon nitride film 14 is selectively etched, at which time the silicon substrates 12 and 13 are lifted up (e) in FIG. 2. The silicon substrates 12 and 13 are etched using an etching solution (HF: HNO ₃ : CH ₃ COOH = 1: 3: 8) ((f) in FIG. 2). The etch protection film 14 is removed.

At this time, the silicon substrates 12 and 13 are ultra-thin substrate supports, and the silicon layer 11 shows a silicon thin film having a double-sided substrate support (Fig. 2 (g)). FIG. 3 illustrates a process of manufacturing a silicon thin film containing a thin film support lower than a surrounding substrate support by using a multi-layer thin film structure before using a silicon substrate direct bonding method. The silicon layer 21 is deposited on the silicon substrate 22 to a predetermined thickness (Fig. 3 (a)).

The silicon nitride film 24 is deposited on the silicon substrate 23 to a predetermined thickness, and the polycrystalline silicon film 25 is deposited to a predetermined thickness on the upper surface of the silicon nitride film 24, and the silicon oxide film 26 is deposited thereon. Deposition of a predetermined thickness is shown (Fig. 3 (b)).

In addition, the epitaxial method may alternately grow a silicon layer containing a high concentration impurity and a silicon layer containing a low concentration impurity to make a multilayered structure.

Instead of the multilayer thin film structure, a substrate in which a silicon layer containing a low concentration of impurities is thickly grown on a silicon layer containing a high concentration of impurities may be used.

The silicon oxide film 27 and the silicon layer 12 are attached by a silicon substrate direct bonding method (Fig. 3 (c)). The silicon nitride film 27 is deposited on the surface to which the two silicon substrates 22 and 23 are bonded by an etching protection film ((d) of FIG. 3). Polishing to the surface of the silicon layer 21 containing the low concentration impurity (d) of FIG.

After the etching protection layer 27a is coated, the shape is defined to etch the back side, and then the etching protection layer 27 is removed ((f) of FIG. 3). The silicon substrate 23 containing the high concentration impurity is selectively etched by immersing it in the etching solution so that the silicon oxide layer 26 or the silicon nitride layer 24, which is a silicon layer or an etch barrier layer containing the low concentration impurity, is lifted up (g of FIG. )). The silicon nitride film 27a is apply | coated on the whole surface. Then, after the photosensitive film is coated on the rear surface, the shape is defined such that the portion to be left as a thin film support remains (Fig. 3 (h)). The photosensitive film 28 in which the shape was defined is shown. Using this photoresist as a protective film, the silicon layer containing a low concentration of impurities or the material layer silicon nitride film 24 and the polycrystalline microfilm 25 having a multi-layer structure were removed by a dry etching method to contain the microoxide film silicon oxide film 26. Let me Next, the photosensitive film 28, the etch protective film 27a, and the silicon oxide film 26 are removed to produce a silicon thin film having the thin film support 29 (FIG. 3 (i)). Substrates in (e) of FIG. 1, (d) of FIG. 2, and (e) of FIG. 3, which are intermediate processes of silicon thin film production, can be used for other purposes.

A new thin film such as gold (Au), tantalum (Ta), tungsten (W), or silicon oxide film is deposited on the upper layer of the substrate (e) of FIG. 1 or (e) of FIG. pellicle

The present invention has a wide range of applications, such as the production of pressure sensing elements, X-ray masks.

4 shows an X-ray mask manufactured by defining a shape on a silicon thin film substrate which is an X-ray transmission film as an example of practical application.

Thin film support (32 (a) of FIG. 4, below the separation line between the element chip (31 (a) of FIG. 4, (33) of (b) of FIG. 4) and the element chip in the mask) By inserting (34) of FIG. 4B, a large area having a small internal stress can define the shape of many element chips in the silicon thin film substrate.

5 shows a process for producing a thin film, such as a thin film of a silicon oxide film or a silicon nitride film, instead of a silicon thin film. Is deposited, and a polysilicon thin film 43 is deposited thereon (Fig. 5 (a)). After polishing the surface of the polycrystalline silicon thin film 43, the silicon layer 45 containing the low concentration impurities is grown on the silicon substrate 44 containing the high concentration impurities (Fig. 5 (b)). The polycrystalline silicon thin film 43 and the silicon layer 45 are adhered ((c) of FIG. 5). Etch protective films 46a and 46b are deposited on the upper and lower surfaces of the silicon substrates 41 and 44 ((d) of FIG. 5). For selective etching, the shape is defined in the etching protection films 46a and 46b ((e) of FIG. 5). Selective substrate etching is performed using a silicon substrate etching solution (HF: HNO ₃ : CH ₃ COOH = 1: 3: 8) ((f) in FIG. 5). Silicon layers 42 and 45 containing low concentration impurities are removed using a dry etching method or an etching solution (HF: HNO ₃ : CH ₃ COOH = 1: 3: 8) ((g) of FIG. 5). (G) of FIG. 5 is a thin film structure of a silicon oxide film or a silicon nitride film. In Fig. 5 (g), the silicon oxide film or silicon nitride film 43 is a substrate thin film layer, and the silicon substrates 41 and 44 are substrate supports. Of course, here, too, one or more thin film supports 47 can be placed between the substrate supports.

Therefore, by manufacturing the silicon thin film by the silicon substrate direct bonding method of the present invention, it is possible to produce a large area silicon thin film with improved uniformity.

Claims (3)

In the silicon substrate direct bonding method, the silicon layer 1 and the silicon oxide film layer 5 are adhered to each other, the silicon substrate 2 is etched, and the etching protection film 6 is used as an etch stop layer to stop the etching. , Silicon thin film manufacturing method using a silicon substrate direct bonding method comprising the steps of removing the etch barrier film made of the etching protective film (6). The method of manufacturing a silicon thin film using a silicon substrate direct bonding method according to claim 1, wherein a substrate having a multilayer structure is manufactured by using a silicon oxide film, a silicon nitride film, a polycrystalline silicon thin film, or the like. The method of claim 1, wherein the single-sided or double-sided substrate support is formed, or one or more thin film supports are provided in the substrate support.