JP2005039078A - Wafer substrate for sheet substrate structure formation, method for manufacturing the same, and method for manufacturing mems element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wafer substrate for sheet substrate structure formation having a feed through structure suitable for a large aperture wafer process, a method for manufacturing the wafer substrate, and a method for manufacturing an MEMS(Micro-Electro-Mechanical-Systems) element. <P>SOLUTION: This substrate to be used for a wafer process is structured by integrally adhering a main body substrate wafer through an adhesive layer to an auxiliary supporting substrate wafer, and the surface side of the main body substrate wafer is formed with holes and areas where the holes are buried with conductive materials, and the wafer substrate is used for thinning as a wafer substrate for sheet substrate structure formation having a feed through area. This substrate wafer is adhered to another substrate wafer so that an element can be formed in a wafer level. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to a thin plate substrate having a bonded structure suitable for a process for handling large-diameter wafers, and a device manufacturing method using the thin substrate.

In a manufacturing method in which MEMS (Micro-Electro-Mechanical-Systems) elements are collectively formed on a wafer substrate, it is usually necessary to construct a three-dimensional structure as compared with a semiconductor element or integrated circuit manufacturing method using a silicon substrate. Special techniques are used. For example, MEMS uses metal, glass, resin, etc. in addition to silicon as a substrate material, and uses technology to form deep steps and through holes in these, combining elements of the same type or different types of wafer substrates, and so on. Creating.

In addition, since MEMS can construct a device structure (called wafer process packaging) that is hermetically sealed or packaged in a wafer state, there is a great advantage in reducing the cost of the device. Has been done. This technique is described in, for example, “Micromachining and Micromechatronics”, page 59 of Baifukan (issued in June 1992). In wafer process packaging, as a basic technology, a high-precision through-hole processing technology is formed on a substrate wafer to form a feed-through structure on a glass substrate. A variety of technologies, including technology for embedding in silicon, processing a silicon or glass substrate wafer into a thin plate during the manufacturing process, and forming a pattern on the thin plate substrate of glass and silicon by anodic bonding or thermocompression bonding Advanced technology is required. The problem with the above manufacturing technology is that it is necessary to use a substrate wafer that is thicker as the substrate wafer becomes larger in order to ensure mechanical strength so that the wafer does not break during handling in the wafer process. In the process of forming the through-hole for use, the processing time of the through-hole becomes long, the size of the processing hole becomes large and the feedthrough cannot be densified, and the conductive material is difficult to embed because the through-hole is deep, working time However, MEMS has a problem that the effect of cost reduction by mass production cannot be obtained sufficiently even when a large-diameter substrate wafer is used, as in the case of silicon LSI.

When the substrate wafer is made as thin as possible, there is a high probability that the substrate will break during handling of the manufacturing process, and a decrease in yield is unavoidable. Thus, in the MEMS manufacturing process, the thickness of the substrate is not only related to the element performance, but is also an important factor that determines the manufacturing cost. For example, in the manufacturing process of a 6-inch large-diameter wafer, there is a problem that normal handling becomes difficult for a substrate wafer having a thickness of about 500 μm or less.
“Masaki Esashi, et al., Micromachining and Micromechatronics, Baifukan, 1992, p. 59”

An object of the present invention is to provide a manufacturing process capable of reducing the thickness of a feedthrough substrate to a necessary minimum in the structure of a MEMS element. The problems to be solved by the present invention include (1) providing a method for manufacturing a thin plate feedthrough substrate having an auxiliary support substrate, and (2) a thin plate feedthrough substrate having an auxiliary support substrate at a processing temperature during the manufacturing process. (3) To provide a method for reliably and quickly removing the auxiliary support substrate at the end of the manufacturing process.

The basis of the present invention for the above-described problems is characterized in that a thin plate substrate having a feed-through structure is obtained from a main substrate bonded and bonded to an auxiliary support substrate. A wafer bonded using the auxiliary support substrate of the present invention is characterized by using a high heat-resistant material of polyimide as an adhesive so as to withstand the temperature of the manufacturing process. In addition, a germanium layer that is dissolved by wet etching based on hydrogen peroxide is inserted so that the main parts of the bonded wafer can be easily removed from the auxiliary support substrate without deterioration in the manufacturing process. To do. Accordingly, it is an object of the present invention to provide a manufacturing process capable of reducing the thickness of a substrate having a feedthrough to the minimum necessary.

In addition, the substrate used in the wafer process has a structure in which the main substrate wafer and the auxiliary support substrate wafer are bonded and integrated by an adhesive layer, and the main substrate wafer has holes on the surface side and is embedded with a conductive material. It is an object to provide a wafer substrate for forming a thin plate substrate structure characterized by having a region.

The material of the substrate having a feedthrough is preferably a semiconductor crystal such as silicon or GaAs, a metal plate such as Al or Ti, or a composite thereof, in addition to an insulator such as pyrex glass, quartz glass or resin.

The thin plate substrate structure for a wafer process of the present invention provides a thin plate substrate structure forming wafer substrate having a feed-through structure by thinning a main substrate wafer having a hole processed and embedded with a conductive material.

  At least one type of thin substrate structure forming wafer substrate having a feedthrough structure described above is used in a wafer process to form an element structure substrate wafer superposed in a wafer process. The present invention provides a wafer substrate for forming a thin plate substrate structure, wherein a MEMS element or a semiconductor element can be obtained by dividing the element.

  A step of forming holes in the main substrate wafer from the surface, a step of forming a region in which a conductive material is embedded, a step of bonding the wafer substrate and the auxiliary support substrate wafer together by an adhesive layer, and a step of integrating the wafer; The present invention provides a method for producing a wafer substrate for forming a thin-plate substrate structure, characterized in that the wafer substrate is manufactured based on a step of scraping the back surface of the substrate to expose the conductive material.

  A wafer substrate for forming a thin substrate structure manufactured by the manufacturing method described above, a step of bonding another structure wafer substrate to the wafer substrate, a step of processing the structure wafer substrate, and a predetermined thickness , A step of forming a predetermined pattern or electrode on the structure wafer substrate, a step of bonding the wafer substrate to another substrate, and removing the auxiliary substrate and the adhesive layer from the bonded wafer substrate. The present invention provides a method for manufacturing a MEMS device, which is manufactured based on a process.

The main effects of the invention are as follows.
-Since the processing time of the hole processing for forming the feedthrough and the embedding of the conductive material can be significantly reduced, the productivity can be remarkably improved and the cost can be reduced by using this method.
-Since the height of the feedthrough can be designed arbitrarily, the structural design of the element becomes easy. Further, the electrical resistance is improved and the performance of the element can be improved.

An embodiment for manufacturing a MEMS device such as an acceleration sensor using a large-diameter substrate wafer will be described. FIG. 1 is a side sectional view showing a schematic structure of an acceleration sensor. This is composed of a structure of a supporting glass substrate 30, a silicon substrate 20, and a glass substrate 10 with a feedthrough. The supporting glass substrate 30 has a structure having a recessed region 31 and an electrode region. The silicon substrate 20 has a structure having a cantilever 21 as a movable part, a support region, an electrode region, and the like. The substrate 10 with feedthrough has a structure having a glass substrate 11, a feedthrough portion 12 in which a conductive material is filled in a through hole, an electrode region 13, and an electrode terminal 14. The acceleration is detected by moving the cantilever 21 and measuring the capacitance change between the electrode terminals 14. Each of the acceleration sensors is obtained by bonding a wafer-shaped support glass substrate 30, a silicon substrate 20, and a glass substrate 10 with a feedthrough, and dividing the wafer into chips. This manufacturing process includes a method for manufacturing a glass substrate 10 with a feed-through having a thin plate structure according to an embodiment of the present invention. This acceleration sensor can be manufactured by the manufacturing procedure using the wafer substrate shown in FIGS. Hereinafter, this manufacturing method will be described.

The manufacturing method of the glass substrate 10 with a feedthrough is the process of FIGS.
FIG. 2: A thick glass substrate 11 is used to form a thin glass substrate 10 with a feedthrough. This glass material is preferably Pyrex glass.
FIG. 3: An etching mask layer 15 is formed on the surface of the glass substrate 11. This mask requires a mask material that can be used for dry or wet etching, and is usually used by patterning a thin layer of chromium.
FIG. 4: Holes 16 are formed on this surface by dry or wet etching. The depth of the hole is preferably half or less of the thickness of the glass substrate 11.
FIG. 5: A thin metal layer 17 is formed on this surface. This has strong adhesive strength with the glass substrate and is used as the base for electrolytic plating, so usually chromium-nickel is used.
FIG. 6: A conductive layer 18 such as copper is deposited on this surface so that the holes 16 of the glass substrate are sufficiently filled by electrolytic plating. As a technique for embedding the inside of the hole with emphasis, a plating method using a pulse power source or a method of masking a region other than the hole region with a photoresist or the like is used.
Figure 7: Flatten the surface by polishing. The hole is filled with a conductive material such as copper, and a region to be the feedthrough portion 12 and a glass surface are formed.
FIG. 8: A thin resin layer 19 resistant to high temperatures, such as polyimide, is applied to the surface. This is semi-dried and used as an adhesive layer in the next step.
FIG. 9: A silicon auxiliary support substrate 50 used as a reinforcing plate is prepared in order to form a thin glass substrate 10 with a feedthrough. This is a structure in which a groove 51 is formed on one surface, a silicon thermal oxide film is formed on the entire surface, and a germanium layer 52 is uniformly attached to the surface.
FIG. 10: The germanium layer 52 surface of the silicon auxiliary support substrate 50 and the resin layer 19 surface of the glass substrate 11 are bonded.
FIG. 11: The adhered glass substrate 11 is shaved by polishing, and a conductive material such as copper filled in the hole is exposed to form a feedthrough portion 12. An electrode region 13 having a chrome / gold structure is formed on the mirror-finished surface. By this manufacturing process, the basic structure of the glass substrate 10 with a feedthrough having a thin plate structure is formed. The features of this manufacturing method are as follows: (1) The glass substrate is thin, so that the work time for forming the feedthrough structure is short. (2) The thin glass substrate is held by the auxiliary support substrate that can withstand high temperatures. It can be used.

A manufacturing method for bonding a silicon substrate to the glass substrate 10 with feedthrough will be described with reference to FIGS.
FIG. 12: The glass substrate 10 with feedthrough and the silicon substrate 20 are aligned. The silicon substrate 20 is formed on the surface of an SOI substrate 25 composed of a silicon support substrate 22 and a silicon oxide film layer 23.
Figure 13: Both wafer substrates are bonded together by anodic bonding.
FIG. 14: The silicon support substrate 22 of the SOI substrate 25 is completely removed by mechanical polishing or etching technique. In the etching finish, the silicon oxide film layer 23 functions as an etching stopper.
FIG. 15: The silicon oxide film layer 23 is removed by etching, leaving only the silicon substrate 20 on the glass substrate 10 with feedthrough.
A method for manufacturing an acceleration sensor by bonding a glass substrate 10 with a feedthrough and a silicon substrate 20 and then bonding a glass substrate will be described with reference to FIGS.
FIG. 16: The surface of the silicon substrate and the surface of the supporting glass substrate 30 are bonded together by anodic bonding.
FIG. 17: Remove the silicon auxiliary support substrate 50 from the substrate by immersing it in an aqueous hydrogen peroxide solution. This uses the principle that an aqueous hydrogen peroxide solution dissolves the germanium layer 52 but does not dissolve other materials.
FIG. 18: The resin layer 19 on the glass substrate 10 with feedthrough remaining after the removal is removed by etching. This is usually removed in an oxygen atmosphere plasma atmosphere.
FIG. 19: The electrode terminal 14 is formed by electrolytic plating on the glass substrate 10 with a feedthrough of the substrate described above, and the acceleration sensor is manufactured at the wafer level.
Thereafter, the device is obtained by dicing into chips.

The wafer substrate for forming a thin plate substrate structure according to the present invention is an example of a thin plate substrate with a feed-through, and is based on a structure manufactured by the steps from FIG. 2 to FIG. The thin plate substrate bonded to the auxiliary support substrate is joined to another wafer substrate through the steps of FIGS. 12 to 16, and then the auxiliary support substrate and the adhesive layer are removed in the steps of FIGS. 17 and 18, respectively. A wafer substrate of a MEMS element having a structure using a thin plate substrate is formed. By using such a technique, it is clear that the wafer substrate for forming a thin substrate structure can be processed in the same way as a conventional process even in a manufacturing process of a large-diameter wafer of 4 inches or more. It is clear that the thin substrate structure forming wafer substrate and the device manufacturing method using the same according to the present invention can be adapted to a mass production line, and the effect of greatly reducing the manufacturing cost is very high.

An embodiment for manufacturing a laminated device by laminating wafers such as thinned LSI using a large-diameter substrate wafer will be described. FIG. 23 is a side sectional view showing a schematic structure of a laminated device composed of thinned LSIs 150, 151, and 152. The example of the present invention provides a method for forming a feedthrough on a wafer such as an LSI, and the principle is basically the same as the method for manufacturing the glass substrate 10 with a feedthrough described in the first embodiment. This manufacturing method will be described with reference to the side sectional views of FIGS.

FIG. 20 shows a silicon hole formed on the surface of a finished wafer such as an LSI, an insulating film 106 is formed on the side wall of the hole, a conductive layer 105 such as metal is embedded, and after planarization, a silicon-LSI substrate is formed. 1 is a side cross-sectional view of a wafer 100 formed in a process of connecting an LSI portion 102 and a wiring layer portion 103 of a wire 101 with a wiring electrode 107. FIG. A feedthrough portion 110 is finally formed by the insulating film 106 on the side wall of the hole and the conductor layer 105 such as metal.
FIG. 21 is a side sectional view of a wafer formed by bonding the wafer 100 formed in FIG. 20 to the silicon auxiliary support substrate 200 by the same method as in the first embodiment. The auxiliary support substrate has a structure in which the groove 201, the silicon thermal oxide film on the entire surface, and the germanium layer 202 are uniformly attached on the surface. A resin layer 119 that is resistant to high temperatures, such as polyimide, is used as an adhesive layer. The back surface of the bonded LSI wafer or the like is scraped by high-speed dry etching of silicon to expose a conductive material such as copper filled in the hole, thereby forming a feedthrough portion. A silicon oxide film layer 130 is formed on the mirror-finished surface, contact holes are formed, and an electrode region 140 made of chromium, gold, or the like is formed. Through this process, an ultra-thin wafer 150 having a feed-through structure in a wafer such as an LSI is obtained.
FIG. 22 is a side cross-sectional view of a structure in which another ultrathin wafer 151 is stacked on an ultrathin wafer 150 by repeating the same method. The front ultra-thin wafer 150 and the rear wafer 151 are connected and bonded by a metal layer 301 that is easily melt-bonded such as a metal that is easily melted such as solder or gold. In the step of forming this, after the bonding, the silicon substrate is thinly polished to obtain an ultrathin wafer 151.
In FIG. 23, after repeating such a process to laminate the ultrathin wafers 150, 151, and 152, the auxiliary support substrate 200 is removed therefrom to form metal layers 300 and 303 that are easily melted such as solder. Thus, a stacked structure is formed. The method for removing them from the auxiliary support substrate is the same as in the first embodiment.

Although the present invention has been described with reference to the embodiments, this technique is also used for the purpose of simply bonding the main wafer substrate made of silicon to the auxiliary support substrate and reducing the thickness of the main substrate. It goes without saying that it is possible. Specifically, the most suitable method for manufacturing a device by thinning the silicon wafer to the limit is mechanical polishing and subsequent strain removal using high-speed dry etching of silicon. The configuration of the present invention can withstand, and it is easy to remove the auxiliary support substrate, and the support substrate can be used any number of times.

FIG. 3 is a side sectional view showing a schematic structure of the acceleration sensor according to the first embodiment. The sectional side view of the thick glass substrate used in order to form the thin glass substrate 10 with a feedthrough in the manufacturing method of Example 1. FIG. FIG. 3 is a side sectional view in which an etching mask layer is formed on the glass substrate of Example 1 and FIG. 2. FIG. 4 is a side sectional view in which holes 16 are formed in the glass substrate of Example 1 and FIG. 3. FIG. 5 is a side sectional view in which a thin metal layer 17 is formed on the surface of the glass substrate of Example 1 and FIG. FIG. 6 is a side sectional view in which holes 16 of the glass substrate of Example 1 and FIG. 5 are filled with a conductive layer. 7 is a side sectional view in which the surface of the glass substrate of Example 1 and FIG. 6 is made flat. FIG. 8 is a side sectional view in which a resin layer 19 such as polyimide is formed on the surface of the glass substrate of Example 1 and FIG. 7. FIG. 3 is a side cross-sectional view of a structure which is a reinforcing plate used in the manufacturing process of Example 1 and has a germanium layer formed on one surface with unevenness. FIG. 10 is a side sectional view of the structure in which the first embodiment and FIGS. 8 and 9 are bonded together. FIG. 11 is a side cross-sectional view of a structure in which Example 1 and FIG. 10 are shaved to expose a conductive material such as copper filled in a hole to form a feedthrough portion and to form an electrode wiring layer. FIG. 12 is a side sectional view of the configuration in which the SOI substrate is aligned with that in Embodiment 1 and FIG. FIG. 13 is a side sectional view of a structure in which the wafer substrates of Example 1 and FIG. 12 are bonded by anodic bonding. FIG. 14 is a side sectional view of the structure in which the silicon support substrate of the SOI substrate in FIG. FIG. 15 is a side sectional view of the structure obtained by removing the silicon oxide film layer of Example 1 and FIG. FIG. 16 is a side sectional view of the structure in which the surface of the silicon substrate and the surface of the supporting glass substrate in Example 1 and FIG. 15 are bonded by anodic bonding. FIG. 17 is a side cross-sectional view of a structure in which the support substrate of Example 1 and FIG. 16 is removed. FIG. 18 is a side cross-sectional view of a structure in which the resin layer of Example 1 and FIG. 17 is removed. FIG. 19 is a side sectional view of the structure in which the electrode terminal 14 is formed on the glass substrate 10 with a feedthrough in FIG. In the manufacturing process of Example 2, a silicon hole is formed from the surface of the finished LSI wafer, an insulating film is formed on the side wall of the hole, a conductor layer such as metal is embedded, and after planarization, The side sectional view of the wafer formed in the process which connected the LSI part and wiring layer part of the silicon substrate with the wiring electrode. FIG. 21 is a side sectional view of a wafer in which the wafer formed in FIG. 20 is bonded to an auxiliary support substrate in the manufacturing process of Example 2; FIG. 10 is a side sectional view of a structure in which another ultrathin wafer 151 is stacked on an ultrathin wafer 150 in the manufacturing process of the second embodiment. FIG. 5 is a side sectional view showing a schematic structure of a laminated device made of a thinned LSI or the like of Example 2.

Explanation of symbols

10: Glass substrate with feedthrough 11: Glass substrate 12: Feedthrough portion 13: Electrode region 14: Electrode terminal 15: Etching mask layer 16: Hole 17: Metal layer 18: Conductive layer 19: Resin layer 20: Silicon substrate 21: Cantilever 22: silicon support substrate 23: silicon oxide film layer 25: SOI substrate 30: support glass substrate 50, 200: auxiliary support substrate 51: groove 52: germanium layer 100: wafer 101: silicon-LSI substrates 150, 151, 152: Ultra-thin wafers 300, 301, 302, 303: Metal layers that are easy to melt

Claims (6)

The substrate used in the wafer process has a structure in which the main substrate wafer and the auxiliary support substrate wafer are bonded and integrated with an adhesive layer, and the main substrate wafer has a hole on the surface side and a region embedded with a conductive material. A wafer substrate for forming a thin-plate substrate structure, characterized by having:
Thin board structure. 2. A wafer substrate for forming a thin substrate structure for a wafer process according to claim 1, wherein the wafer substrate has a feed-through region by thinning using a wafer substrate having a structure having a hole and a region in which a conductive material is embedded. A wafer substrate for forming a thin plate substrate structure. A thin wafer structure for a wafer process formed by the manufacturing method according to claim 1 and 2, comprising an insulator wafer such as glass and a semiconductor wafer such as silicon or GaAs. Wafer substrate. A substrate used in a wafer process, wherein at least one thin substrate wafer according to claim 1 is used to form an element structure substrate wafer superposed in a wafer process, and this is divided into each element. A wafer substrate for forming a thin plate substrate structure, characterized in that a MEMS element or a semiconductor element can be obtained by: A step of forming holes in the main substrate wafer from the surface, a step of forming a region in which a conductive material is embedded, a step of bonding the wafer substrate and the auxiliary support substrate wafer together by an adhesive layer, and a step of integrating the wafer; A method for producing a wafer substrate for forming a thin substrate structure, comprising: a step of shaving a back surface of a substrate to expose the conductive material. 6. A thin substrate structure forming wafer substrate manufactured by the manufacturing method according to claim 5, a step of bonding another structure wafer substrate to the wafer substrate, a step of processing the structure wafer substrate, and a predetermined A step of processing the thickness, a step of forming a predetermined pattern or electrode on the structure wafer substrate, a step of bonding the wafer substrate to another substrate, and the auxiliary substrate and the adhesive layer from the bonded wafer substrate. And a step of removing the MEMS element.