JP2008103386A - Method for manufacturing stencil mask for ion implantation - Google Patents

Abstract

In an ion implantation process using a stencil mask for ion implantation performed in semiconductor device fabrication, a critical defect of the stencil mask for ion implantation, which is a deflection of a membrane caused by ion beam heat generation, is reduced, and excellent heat resistance is achieved. The present invention provides a method of manufacturing a stencil mask for ion implantation that has high performance, durability, and ion implantation accuracy.
A step of forming a first thin film layer (22) and a second thin film layer (23) in this order on at least one surface of a support layer (21), and on the other surface of the support layer (21). The step of forming the opening (26), and the formation of the through hole pattern 1 (28) for ion implantation in the second thin film layer (23), and then the second thin film layer (23) as an etching mask, the first thin film layer ( 22) forming a through-hole pattern for ion implantation 2 (29), and a method for producing a stencil mask for ion implantation.
[Selection] Figure 2

Description

  The present invention relates to a method for manufacturing a stencil mask for ion implantation used in an ion implantation step in a semiconductor device fabrication step.

  The semiconductor device manufacturing process includes a process of doping a single crystal silicon substrate with an impurity element such as B or P. As a method for doping this impurity element, there are mainly a thermal diffusion method and an ion implantation method. However, since the thermal diffusion method has a problem such as variation in resistance, it has recently been doped with an impurity element with higher accuracy than the thermal diffusion method. An ion implantation method capable of achieving the above is often used.

  The conventional ion implantation method is a method in which regions other than the pattern region on the substrate are masked with a resist by photolithography, and ions are implanted only into the pattern region. When this method is used, many processes such as lithography processes such as resist application, pattern exposure, and development, resist removal processes that become unnecessary after the ion implantation process, and substrate cleaning processes are included. There was a problem that time became long. In addition, since an apparatus is required for each process, there is also a problem that the area occupied by the apparatus is large.

  In order to solve the above problems, research on ion implantation technology using a stencil mask for ion implantation has been conducted in recent years. This method is a method in which ions are implanted by making an ion beam formed in the shape of a through hole pattern on a stencil mask for ion implantation enter a substrate.

FIG. 1 is a diagram for explaining a manufacturing process of a conventional ion implantation stencil mask.
A conventional ion implantation stencil mask (17) is fabricated using the SOI wafer (14) shown in FIG. This SOI wafer (14) has three layers: a support layer (11) made of single crystal silicon, an etching stopper layer (12) made of a silicon oxide film, and a thin film layer (13) made of single crystal silicon. As shown in FIG. 1B, the conventional stencil mask (17) for ion implantation has an opening (15) on the back surface and a thin film layer (13) (hereinafter referred to as a membrane) formed as a single-layer free-standing film. This is a structure having a through-hole pattern (16).

  However, when ion implantation is performed using a conventional stencil mask for ion implantation manufactured using a three-layer SOI wafer as described above, there is a problem that the membrane bends due to heat generated by the ion beam. . When the membrane bends, the pattern position accuracy deteriorates significantly. In the stencil mask for ion implantation, improvement of the heat resistance and durability of the mask is a big problem.

As a measure for improving mask heat resistance and durability in an ion implantation stencil mask, for example, a method of providing an ion absorption layer on one side or both sides of a membrane has been proposed (see Patent Document 1). Although this method is effective, after forming the membrane, an ion absorption layer is formed on the membrane by sputtering or the like to produce a stencil mask for ion implantation. It is also formed on the opening side wall in the through hole pattern on the membrane. When the film is formed, the dimension of the pattern may change. In addition, since the film is formed only in the vicinity of the edge of the opening side wall in the through hole pattern on the membrane, the edge of the implantation pattern is obtained when ion implantation is performed using the stencil mask for ion implantation produced by this method. There is also the problem of blurring.
JP 2004-158527 A

  The present invention has been made in view of the above problems, and in an ion implantation process using a stencil mask for ion implantation performed in semiconductor device fabrication, membrane deflection caused by ion beam heat generation is referred to as stencil for ion implantation. An object of the present invention is to provide a method for manufacturing a stencil mask for ion implantation that reduces fatal defects of the mask and has excellent heat resistance, durability, and ion implantation accuracy.

  In order to achieve the above object in the present invention, the method for manufacturing a stencil mask for ion implantation according to claim 1 forms the first thin film layer and the second thin film layer in this order on at least one surface of the support layer. A step of forming an opening on the other surface of the support layer, and forming an ion implantation through-hole pattern 1 in the second thin film layer, and then forming ions in the first thin film layer using the second thin film layer as an etching mask. And a step of forming the through-hole pattern for injection 2.

  In the method for manufacturing a stencil mask for ion implantation according to claim 2, the support layer is single crystal silicon, the first thin film layer is diamond, and the second thin film layer is polycrystalline silicon. It is characterized by.

  In the method for manufacturing a stencil mask for ion implantation according to claim 3, the support layer is monocrystalline silicon, the first thin film layer is copper, and the second thin film layer is polycrystalline silicon. It is characterized by.

  The stencil mask for ion implantation according to claim 4 has a membrane composed of two layers of a first thin film layer and a second thin film layer on one surface of the support layer, and an opening on the other surface of the support layer. And a stencil mask for ion implantation having a through-hole pattern for ion implantation in the first thin film layer and the second thin film layer.

  According to the method for manufacturing a stencil mask for ion implantation of the present invention, it is possible to obtain an stencil mask for ion implantation in which a membrane is composed of a first thin film layer and a second thin film layer. In particular, by selecting a material with high thermal conductivity as the material constituting the first thin film layer and the second thin film layer, the heat capacity of the membrane in the stencil mask for ion implantation is produced using a three-layer SOI wafer. It is possible to significantly increase the heat capacity of the membrane in the conventional ion implantation stencil mask. Therefore, the critical defect of the stencil mask for ion implantation, which is the bending of the membrane due to the ion beam heat generation, is greatly reduced, and a mask having excellent heat resistance and durability can be obtained.

  In addition, when using the stencil mask for ion implantation produced by the method for manufacturing a stencil mask for ion implantation of the present invention, ion implantation with significantly improved accuracy is possible compared to the case of using a conventional stencil mask for ion implantation. As a result, semiconductor devices and the like can be manufactured with a high yield.

  Hereinafter, an example of the manufacturing method of the stencil mask for ion implantation of this invention is demonstrated. FIGS. 2A to 2F are schematic cross-sectional views showing an example of a method for manufacturing a stencil mask for ion implantation according to the present invention.

  First, the first thin film layer (22) and the second thin film layer (23) are formed in this order on the upper surface (one surface) of the support layer (21) by sputtering, CVD, or the like (FIG. 2 (a)). reference). The support layer (21) is preferably single crystal silicon.

  Photoresist is applied to the lower surface (the other surface) of the support layer (21) of the substrate (24) thus obtained by using a spinner or the like to form a photosensitive layer, and patterning treatment such as pattern exposure and development is performed. A pattern (25) is formed (see FIG. 2B).

  Next, using the resist pattern (25) as an etching mask, the support layer (21) is removed by dry etching, wet etching, or the like, thereby forming an opening (26). Thereby, the membrane which consists of two layers, a 1st thin film layer (22) and a 2nd thin film layer (23), is formed. The first thin film layer (22) is used as an etching stopper when the support layer (21) is etched. Further, the unnecessary photoresist is removed by oxygen plasma ashing or the like (see FIG. 2C).

  Next, an electron beam resist is applied to the upper surface of the second thin film layer (23) which becomes the membrane by a spinner or the like to form a photosensitive layer, and patterning processing such as electron beam drawing and development is performed to form a resist pattern (27 ) (See FIG. 2 (d)).

  Next, by using the resist pattern (27) as an etching mask, the second thin film layer (23) is etched by dry etching or the like, and then the resist pattern (27) is removed by oxygen plasma ashing or the like to obtain the second thin film layer. The through-hole pattern 1 (28) for ion implantation is formed in (23) (see FIG. 2 (e)).

  Next, the first thin film layer (22) is etched by dry etching, wet etching or the like using the second thin film layer (23) as an etching mask, and the ion implantation through-hole pattern 2 is formed on the first thin film layer (22). (29) is formed. As a result, a stencil mask (210) for ion implantation in which the membrane is composed of two layers of the first thin film layer (22) and the second thin film layer (23) is obtained (see FIG. 2 (f)).

  Here, in a conventional ion implantation stencil mask fabricated using an SOI wafer, the membrane is made of single crystal silicon. In order to use the conventional technique for forming a through hole pattern for ion implantation on the membrane made of single crystal silicon as it is, as a material constituting the second thin film layer (23), for example, silicon is desirable. In particular, it is desirable to use single crystal silicon, but if it is difficult to form single crystal silicon on the upper surface of the first thin film layer (22), polycrystalline silicon can be preferably used.

  Moreover, as a material which comprises a 1st thin film layer (22), it is desirable to use a material with high heat conductivity in order to reduce the thermal deflection of a membrane. Further, the step of forming the ion implantation through-hole pattern 2 (29) in the first thin film layer (22) is performed using the second thin film layer (23) as an etching mask, so that the second thin film layer (23) is etched. It is desirable to use a material with high selectivity. For example, when silicon is used for the second thin film layer (23), diamond, copper, or the like can be suitably used as a material constituting the first thin film layer (22).

  The dimension of the ion implantation through-hole pattern is preferably defined by the dimension of the ion implantation through-hole pattern 1 (28). Since the first thin film layer (22) is a layer formed to reduce the thermal deflection of the membrane, strict accuracy is not required for the dimension of the ion implantation through hole pattern 2 (29). The dimension of the through hole pattern 2 (29) may be larger than that of the ion implantation through hole pattern 1 (28).

  In the above description, the method of processing the first thin film layer (22) and the second thin film layer (23) after processing the support layer (21) has been described. Conversely, the first thin film layer (22) and the second thin film layer (22) are processed. It is also possible to process the support layer (21) after processing the thin film layer (23).

  Hereinafter, the method for producing the stencil mask for ion implantation of the present invention will be described with reference to examples.

  First, a first thin film layer (22) made of diamond having a thickness of 10 μm is formed on the upper surface of a support layer (21) made of single crystal silicon having a thickness of 500 μm by CVD, and the first thin film layer (22) is formed. A second thin film layer (23) made of polycrystalline silicon having a thickness of 10 μm was formed on the upper surface by sputtering (see FIG. 2 (a)).

  A photoresist is applied to the lower surface of the support layer (21) of the substrate (24) thus obtained by a spinner to form a photosensitive layer having a thickness of 20 μm, and patterning treatment such as pattern exposure and development is performed to obtain a resist pattern (25 ) Was formed (see FIG. 2 (b)).

  Next, the support layer (21) was removed by etching by dry etching using a fluorocarbon mixed gas plasma using the resist pattern (25) as an etching mask, thereby forming an opening (26). Thereby, the membrane which consists of two layers, a 1st thin film layer (22) and a 2nd thin film layer (23), was formed. Further, the unnecessary photoresist was removed by oxygen plasma ashing (see FIG. 2C).

  Next, an electron beam resist is applied on the upper surface of the second thin film layer (23), which becomes a membrane, to form a photosensitive layer having a thickness of 1.0 μm, and patterning processing such as electron beam drawing and development is performed. A resist pattern (27) was formed (see FIG. 2 (d)).

  Next, the second thin film layer (23) is etched by dry etching using a fluorocarbon-based mixed gas plasma using the resist pattern (27) as an etching mask, and then the resist pattern (27) is removed by oxygen plasma ashing. Thereby, the through-hole pattern 1 (28) for ion implantation was formed in the 2nd thin film layer (23) (refer FIG.2 (e)).

  Next, the first thin film layer (22) is etched by dry etching using a mixed gas plasma containing oxygen using the second thin film layer (23) as an etching mask, and ions are implanted into the first thin film layer (22). A through-hole pattern 2 (29) was formed. As a result, a stencil mask (210) for ion implantation in which the membrane was composed of two layers of the first thin film layer (22) and the second thin film layer (23) was obtained (see FIG. 2 (f)).

  When ion implantation was performed using the stencil mask for ion implantation (210) produced by the above method under the conditions of heat input of 50 W and implantation time of 0.5 sec, the amount of deflection of the membrane in the stencil mask for ion implantation (210). Was 1 μm or less.

  Further, for comparison, a support layer (11) made of single crystal silicon having a thickness of 500 μm, an etching stopper layer (12) made of a silicon oxide film having a thickness of 1.0 μm, and a thin film layer made of single crystal silicon having a thickness of 20 μm ( 13) Using the three-layer 100 mmΦ SOI wafer (14) (see FIG. 1A), the same pattern as the ion implantation through-hole pattern 1 (28) is provided on the thin film layer (13). A conventional stencil mask (17) for ion implantation (see FIG. 1B) was produced.

  When ion implantation was performed using the above-described conventional ion implantation stencil mask (17) under the conditions of heat input of 50 W and implantation time of 0.5 sec, the amount of membrane deflection in the ion implantation stencil mask (17) was It was 5 μm. Accordingly, the use of the stencil mask for ion implantation produced by the method for manufacturing a stencil mask for ion implantation of the present invention allows the membrane to bend at the time of ion implantation as compared with the case of using a stencil mask for ion implantation having a conventional structure. It was confirmed that the amount could be greatly reduced.

According to the method for manufacturing a stencil mask for ion implantation of the present invention, the fatal defect of the stencil mask for ion implantation, which is the bending of the membrane due to ion beam heat generation, is greatly reduced, and it has excellent heat resistance and durability. Since a mask can be obtained, it is useful for a step of doping an impurity element into a single crystal silicon substrate, for example, in a semiconductor device manufacturing step.
In addition, the ion implantation stencil mask produced by the method for producing an ion implantation stencil mask of the present invention enables ion implantation with greatly improved accuracy, and as a result, manufacture of semiconductor devices and the like can be performed at a high yield. Can be useful.

It is a figure for demonstrating the manufacturing process of the conventional stencil mask for ion implantation, (a) is typical structure sectional drawing which shows an example of SOI wafer, (b) is an example of the conventional stencil mask for ion implantation. It is a schematic structure sectional view shown. (a)-(f) is typical structure sectional drawing which shows an example of the manufacturing method of the stencil mask for ion implantation of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11, 21 ... Support layer, 12 ... Etching stopper layer, 13 ... Thin film layer, 14 ... SOI wafer, 15, 26 ... Opening, 16 ... Through-hole pattern, 17, 210 ... For ion implantation Stencil mask, 22 ... 1st thin film layer, 23 ... 2nd thin film layer, 24 ... Substrate, 25, 27 ... Resist pattern, 28 ... Through hole pattern for ion implantation, 29 ... Through for ion implantation Hole pattern 2.

Claims (4)

  Forming a first thin film layer and a second thin film layer on at least one surface of the support layer in this order; forming an opening on the other surface of the support layer; and implanting ions into the second thin film layer Forming a through-hole pattern 2 for ion implantation in the first thin-film layer using the second thin-film layer as an etching mask after forming the through-hole pattern 1 for use, and a method for producing a stencil mask for ion implantation, .   2. The method for manufacturing a stencil mask for ion implantation according to claim 1, wherein the support layer is single crystal silicon, the first thin film layer is diamond, and the second thin film layer is polycrystalline silicon.   2. The method for manufacturing a stencil mask for ion implantation according to claim 1, wherein the support layer is single crystal silicon, the first thin film layer is copper, and the second thin film layer is polycrystalline silicon.   The support layer has a membrane composed of two layers, a first thin film layer and a second thin film layer, has an opening on the other surface of the support layer, and the first thin film layer and the second thin film layer. A stencil mask for ion implantation having a through hole pattern for ion implantation.

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