JP2011171655A - Stencil mask for ion implantation and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stencil mask for ion implantation, having superior heat resistance or durability and improving the ion implantation accuracy by reducing the defect of a stencil mask for ion implantation, such as, membrane deflection due to the heating of an ion beam, and to provide a low-cost method for manufacturing the stencil mask for ion implantation. <P>SOLUTION: A stencil mask 113 for ion implantation is provided with a support layer 11 and a first thin film layer 12. The support layer 11 is provided with a second thin film layer 15, formed by carrying out working from the face opposite to the face on which the first thin film layer 12 is formed to the intermediate part of the thickness direction of the support layer 11, and the first thin-film layer 12 is provided with a first through-hole pattern 112 for ion implantation configured of a plurality of first through-holes for ion implantation, and the second thin-film layer 15 is provided with a second through-hole pattern 18 for ion implantation configured of a plurality of second through-holes for ion implantation, and the position of each of the first through-holes for ion implantation matches that of each of the second through-holes for ion implantation. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a stencil mask for ion implantation and a manufacturing method thereof.

  The semiconductor device manufacturing process includes a process of doping a single crystal silicon substrate with an impurity element such as B (Boron) or P (Phosphor). As a method of 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, the impurity element doping is more highly accurate than the thermal diffusion method recently. An ion implantation method capable of achieving the above is often used.

  The conventional ion implantation method is a method in which a region outside a pattern region on a substrate is masked with a resist by photolithography, and ion implantation is performed only on the pattern region. When this method is used, it includes many processes such as a lithography process such as resist application, pattern exposure, and development, a resist removal process that is no longer necessary after the ion implantation process, and a substrate cleaning process. There was a problem that the device manufacturing 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 technique is a method of implanting ions by causing an ion beam formed in the shape of a through-hole pattern on a stencil mask for ion implantation to enter a substrate.

  An example of a conventional ion implantation stencil mask is shown in FIG. The stencil mask 37 for ion implantation is manufactured using an SOI (Silicon-On-Insulator) wafer 34 shown in FIG. This SOI wafer 34 has three layers: a support layer 31 made of single crystal silicon, an etching stopper layer 32 made of a silicon oxide film, and a thin film layer 33 made of single crystal silicon.

  In the conventional stencil mask 37 for ion implantation, an opening 35 is formed in the support layer 31 and the etching stopper layer 32 as shown in FIG. 3B by processing the SOI wafer 34 in FIG. Thus, the thin film layer 33 (hereinafter referred to as a membrane) that has become a single-layer self-supporting film has a through hole 36.

JP 2004-158527 A

  However, when ion implantation is performed using the stencil mask 37 for ion implantation manufactured using the three-layer SOI wafer 34 as described above, there is a problem that the membrane is bent due to heat generated by the ion beam. is there. When the membrane is bent, not only the position accuracy of the pattern region to be ion-implanted is greatly deteriorated, but also the bent membrane comes into contact with the implantation substrate and the membrane may be destroyed. Thus, in the stencil mask for ion implantation, improvement of the heat resistance and durability of the mask is a problem.

  As a measure for improving the heat resistance and durability of the stencil mask for ion implantation, for example, a method of providing an ion absorption layer on one side or both sides of the membrane has been proposed (see Patent Document 1). Although this method is effective, it is a method of forming an ion absorption layer on the membrane by sputtering after forming the membrane, and it is necessary to precisely control the stress and film thickness of the thin film. Moreover, the dimension of a pattern may change by forming into a film on the opening side wall of the through-hole pattern on a membrane. Furthermore, since the stress of the thin film changes with time, even if the initial stress is 0 or more, it gradually becomes a compressive stress, which may cause the membrane on which the thin film is formed to bend.

  The present invention has been made in view of the above problems, and in the ion implantation process using the ion implantation stencil mask, defects in the ion implantation stencil mask due to membrane deflection caused by the heat generation of the ion beam are reduced, An object of the present invention is to provide a stencil mask for ion implantation that has excellent heat resistance and durability and improves ion implantation accuracy, and an inexpensive manufacturing method thereof.

  In order to achieve the above object, the invention of claim 1 includes a support layer and a first thin film layer provided on one surface of the support layer, and the support layer is formed by the first thin film layer. A second thin film layer formed by processing from a surface opposite to the formed surface to an intermediate portion in the thickness direction of the support layer, wherein the first thin film layer is for a plurality of first ion implantations. The first thin film layer has a second ion implantation through-hole pattern composed of a plurality of second ion implantation through-holes; and The positions of the first through holes for ion implantation and the second through holes for ion implantation are the same.

  According to a second aspect of the present invention, the dimension of the second ion implantation through hole is larger than the dimension of the first ion implantation through hole.

  The invention according to claim 3 is the stencil mask for ion implantation according to claim 1 or 2, wherein the support layer and the second thin film layer are made of single crystal silicon, and the first thin film layer is made of diamond. And

  According to a fourth aspect of the present invention, there is provided a step of forming the first thin film layer on the support layer, and the support layer in a thickness direction of the support layer from a surface opposite to the surface on which the first thin film layer is formed. Forming a second thin film layer by processing up to an intermediate portion, and forming a first ion implantation through hole pattern comprising a plurality of first ion implantation through holes in the first thin film layer And forming a second ion implantation through-hole pattern comprising a plurality of second ion implantation through-holes in the second thin film layer, and each of the first ion implantation through-holes and the Each second ion implantation through-hole is characterized in that the position is matched.

  According to a fifth aspect of the present invention, in the method for manufacturing the stencil mask for ion implantation according to the fourth aspect, the second thin film layer is formed with front and back overlay marks together with the second ion implantation through hole pattern, An alignment mark is formed on the first thin film layer using the front and back overlay marks, and the first ion implantation through-hole pattern is formed on the first thin film layer using the alignment mark. It is characterized by doing.

  According to a sixth aspect of the present invention, in the method of manufacturing a stencil mask for ion implantation according to the fourth or fifth aspect, the support layer and the second thin film layer are made of single crystal silicon, and the first thin film layer is made of diamond. It is characterized by that.

  In the stencil mask for ion implantation of the present invention, the membrane is composed of two layers of the first thin film layer and the second thin film layer. The heat capacity of the membrane in the ion implantation stencil mask is larger than the heat capacity of the membrane of the conventional ion implantation stencil mask manufactured using a three-layer SOI wafer. For this reason, the defect of membrane bending due to heat generation of the ion beam is greatly reduced, and the stencil mask for ion implantation having excellent heat resistance and durability is obtained.

  Moreover, since the dimension of the through-hole pattern for ion implantation in the stencil mask for ion implantation of the present invention may be defined by the first through-hole pattern for ion implantation formed in the first thin film layer, The dimension of the second ion implantation through hole pattern to be formed can be larger than the dimension of the first ion implantation through hole pattern. Thereby, the thickness of the second thin film layer can be increased, and the heat resistance and durability of the membrane can be further increased.

  Moreover, since the manufacturing method of the stencil mask for ion implantation of this invention is a simple method, the stencil mask for ion implantation which has said outstanding heat resistance and durability can be manufactured cheaply.

  Further, by using the stencil mask for ion implantation according to the present invention, ion implantation with high accuracy becomes possible. As a result, semiconductor devices and the like can be manufactured with a high yield.

(a)-(e) is typical structure sectional drawing which shows a part of example of the manufacturing method of the stencil mask for ion implantation of this invention. (a)-(d) is typical structure sectional drawing which shows a part of example of the manufacturing method of the stencil mask for ion implantation of this invention. (a) is a schematic cross-sectional view showing an example of an SOI wafer, and (b) is a schematic cross-sectional view showing an example of a conventional stencil mask for ion implantation.

  Hereinafter, the stencil mask for ion implantation which concerns on embodiment of this invention is demonstrated in detail, referring FIG.1 and FIG.2 with the manufacturing method.

  First, as shown in FIG. 1A, a substrate 13 provided with a first thin film layer 12 on a support layer 11 is prepared.

  Here, for example, single crystal silicon can be suitably used as the support layer 11 in order to use as much as possible the processing technique in the conventional ion implantation stencil mask manufactured using the SOI wafer. When single crystal silicon is selected as the material constituting the support layer 11, the support layer 11 may contain impurities such as boron and phosphorus.

  Further, as a material constituting the first thin film layer 12, it is desirable to use a material having high thermal conductivity and high mechanical strength in order to reduce thermal deflection of the membrane. For example, diamond or the like can be suitably used as a material constituting the first thin film layer 12.

  Next, as shown in FIG. 1B, a photoresist or the like is applied to the lower surface of the support layer 11 with a spinner or the like to form a photosensitive layer (not shown), and pattern exposure, development, etc. are performed on the photosensitive layer. A patterning process is performed to form an etching mask 14.

  Next, as shown in FIG. 1 (c), the support layer 11 is removed by etching the portion excluding the periphery to the middle in the thickness direction by dry etching or wet etching using the etching mask 14. Then, the second thin film layer 15 is formed. Further, the etching mask 14 that has become unnecessary is removed.

  Here, the surface of the second thin film layer 15 may not be completely flat, but the thickness of the second thin film layer 15 is preferably as thick as possible in order to reduce membrane bending.

  Next, as shown in FIG. 1 (d), an electron beam resist or the like is applied to the lower surface of the second thin film layer 15 formed as described above with a spray coater or the like to form a photosensitive layer (not shown). Then, the etching mask 16 is formed by performing patterning processing such as electron beam drawing and development on the photosensitive layer.

  Next, as shown in FIG. 1 (e), the second thin film layer 15 is etched by dry etching or the like using the etching mask 16, and then the etching mask 16 that is no longer needed is removed and the front and back surfaces are overlapped. A second ion implantation through hole pattern 18 including a mark 17 and a plurality of second ion implantation through holes is formed.

  Here, when the second thin film layer 15 is etched, the first thin film layer 12 serves as an etching stopper layer.

  In addition, since the dimension of the ion implantation through hole in the ion implantation stencil mask 113 is defined by the first ion implantation through hole formed in the first thin film layer 12, the second ion film formed in the second thin film layer 15 has a first dimension. The dimension of the second ion implantation through hole may be larger than the dimension of the first ion implantation through hole to be formed later.

  Next, as shown in FIG. 2A, a silicon oxide film or the like (not shown) is formed on the upper surface of the first thin film layer 12, and the front and back overlay marks 17 formed on the second thin film layer 15 are formed. Then, patterning for forming the alignment mark 110 at a desired position of the first thin film layer 12 is performed using a known technique, and the etching mask 19 is formed.

  Next, as shown in FIG. 2B, the first thin film layer 12 is etched by dry etching or the like using the etching mask 19, and then the etching mask 19 that is no longer needed is removed, and an alignment mark is formed. 110 is formed.

  Here, when the first thin film layer 12 is etched, the second thin film layer 15 becomes an etching stopper layer.

  Next, as shown in FIG. 2C, a silicon oxide film or the like (not shown) is formed on the upper surface of the first thin film layer 12, and the alignment mark 110 formed on the first thin film layer 12 is formed. The patterning for forming the first ion implantation through-hole pattern 112 corresponding to the second ion implantation through-hole pattern 18 formed in the second thin film layer 15 in the first thin film layer 12 is known. Then, an etching mask 111 is formed.

  Next, as shown in FIG. 2 (d), the first thin film layer 12 is etched by dry etching or the like using the etching mask 111, and a plurality of second films whose positions match the respective second ion implantation through holes. A first ion implantation through-hole pattern 112 made of one ion implantation through-hole is formed. Thereafter, the etching mask 111 that has become unnecessary is removed. As a result, a stencil mask 113 for ion implantation in which the membrane is composed of two layers of the first thin film layer 12 and the second thin film layer 15 is obtained.

  In the above description, the manufacturing method of processing the first thin film layer 12 after processing the support layer 11 and the second thin film layer 15 has been described. Conversely, after processing the first thin film layer 12, the support layer 11 is processed. And the manufacturing method etc. which process the 2nd thin film layer 15 are also possible.

  The following examples will explain specific examples of the method for manufacturing the stencil mask for ion implantation of the present embodiment.

  First, as shown in FIG. 1A, a substrate 13 is prepared in which a first thin film layer 12 made of diamond having a thickness of 10 μm is formed on a support layer 11 made of 500 μm thick single crystal silicon by a CVD method. did.

  Next, as shown in FIG. 1B, a photoresist is applied to the lower surface of the support layer 11 with a spinner to form a 20 μm-thick photosensitive layer (not shown), and pattern exposure, development, etc. are performed on this photosensitive layer. The etching mask 14 was formed by performing the patterning process.

  Next, as shown in FIG. 1C, the support layer 11 is etched and removed halfway by dry etching using a fluorocarbon-based mixed gas plasma using the etching mask 14, and the second thin film layer 15 is removed. Formed. The thickness of the formed second thin film layer 15 was 50 μm on average, but had a distribution of ± 2 μm. Furthermore, the etching mask 14 which became unnecessary was removed by wet processing.

  Next, as shown in FIG. 1 (d), an electron beam resist is applied to the lower surface of the second thin film layer 15 formed as described above with a spray coater, and a photosensitive layer (not shown) having a thickness of 1.0 μm. Then, patterning processing such as electron beam drawing and development was performed on the photosensitive layer to form an etching mask 16.

  Next, as shown in FIG. 1 (e), the second thin film layer 15 is etched by dry etching using a fluorocarbon mixed gas plasma using the etching mask 16, and then the etching mask that is no longer needed. 16 was removed by wet processing, and a front and back overlay mark 17 and a second ion implantation through hole pattern 18 were formed. The dimension of the second ion implantation through hole pattern 18 was made 5 μm larger than the dimension of the first ion implantation through hole pattern 112 to be formed later.

  Next, as shown in FIG. 2A, a silicon oxide film (not shown) having a thickness of 0.5 μm is formed on the upper surface of the first thin film layer 12 by sputtering. Patterning for forming the alignment mark 110 at a desired position of the first thin film layer 12 using the formed front and back overlay mark 17 was performed using a known technique, and the etching mask 19 was formed.

  Next, as shown in FIG. 2B, the first thin film layer 12 is etched by dry etching using a mixed gas plasma containing oxygen using the etching mask 19, and then the etching mask 19 that is no longer needed. Was removed by wet etching using hydrofluoric acid to form alignment marks 110.

  Next, as shown in FIG. 2C, a silicon oxide film (not shown) having a thickness of 0.5 μm is formed on the upper surface of the first thin film layer 12 by a sputtering method. The first ion implantation through-hole pattern 112 corresponding to the second ion implantation through-hole pattern 18 formed in the second thin film layer 15 using the formed alignment mark 110 is formed in the first thin film layer 12. Patterning for forming was performed using a known technique to form an etching mask 111.

  Next, as shown in FIG. 2 (d), the first thin film layer 12 is etched by dry etching using a mixed gas plasma containing oxygen using an etching mask 111, and a first ion implantation through hole pattern is formed. 112 was formed. Thereafter, the unnecessary etching mask 111 was removed by wet etching using hydrofluoric acid.

  By the above method, the stencil mask 113 for ion implantation of the present invention in which the membrane was composed of two layers of the first thin film layer 12 and the second thin film layer 15 was obtained.

DESCRIPTION OF SYMBOLS 11, 31 ... Support layer 12 ... 1st thin film layer 13 ... Substrate 14, 16, 19, 111 ... Etching mask 15 ... 2nd thin film layer 17 ... Front and back overlay mark 18 ... 2nd ion implantation through-hole Pattern 110 ... Alignment mark 112 ... First ion implantation through hole pattern 113, 37 ... Ion implantation stencil mask 32 ... Etching stopper layer 33 ... Thin film layer 34 ... SOI wafer 35 ... Opening 36 ... Through hole

Claims (6)

A support layer and a first thin film layer provided on one surface of the support layer;
The support layer has a second thin film layer formed by processing from a surface opposite to the surface on which the first thin film layer is formed to an intermediate portion in the thickness direction of the support layer,
The first thin film layer has a first ion implantation through-hole pattern including a plurality of first ion implantation through-holes,
The second thin film layer has a second ion implantation through-hole pattern including a plurality of second ion implantation through-holes,
The positions of the first through holes for ion implantation and the second through holes for ion implantation are matched.
A stencil mask for ion implantation.   2. The stencil mask for ion implantation according to claim 1, wherein the dimension of the second ion implantation through hole is larger than the dimension of the first ion implantation through hole.   3. The stencil mask for ion implantation according to claim 1, wherein the support layer and the second thin film layer are made of single crystal silicon, and the first thin film layer is made of diamond. Forming a first thin film layer on the support layer;
Forming the second thin film layer by processing the support layer from a surface opposite to the surface on which the first thin film layer is formed to an intermediate portion in the thickness direction of the support layer;
Forming a first ion implantation through-hole pattern comprising a plurality of first ion implantation through-holes in the first thin film layer;
Forming a second ion implantation through-hole pattern comprising a plurality of second ion implantation through-holes in the second thin film layer,
The positions of the first through holes for ion implantation and the second through holes for ion implantation are matched.
A method for producing a stencil mask for ion implantation, characterized in that: Forming a mark for overlapping the front and back together with the second through-hole pattern for ion implantation in the second thin film layer;
Using the front and back overlay marks on the first thin film layer to form alignment marks,
Forming the first ion implantation through-hole pattern using the alignment mark in the first thin film layer;
The method for producing a stencil mask for ion implantation according to claim 4.   6. The method for producing a stencil mask for ion implantation according to claim 4, wherein the support layer and the second thin film layer are made of single crystal silicon, and the first thin film layer is made of diamond.

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