JPH08258035A - Production of apparatus having fine structure - Google Patents

Abstract

PURPOSE: To form a uniform and translucent temporary protective film long in holding time, easily and perfectly removed and not requiring inspection in high yield with high productivity while reducing the number of processes, equipment investment and cost and eliminating the possibility of pollution without damaging a fine apparatus. CONSTITUTION: In a manufacturing method containing a process wherein a molten film (naphthalene molten film 104) of a sublimable substance solid at the normal temp. under atmospheric pressure is formed to one main surface 103 on which a fine structure is formed and subsequently coold to form a protective film (naphthalene solid film 105) of a structure having at least a solid phase and, thereafter, the protective film is evaporated and removed, a process improving the wettability of the molten film and the fine structure is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a device having a microstructure represented by a micromachine, and more particularly,
The present invention relates to a method for manufacturing a device having an inexpensive and highly reliable microstructure, which prevents contamination or damage to the microstructure.

[0002]

2. Description of the Related Art As a conventional method for manufacturing a microdevice, a method for dicing a semiconductor substrate on which a microdevice or a semiconductor element is formed will be described as an example. FIG. 13 shows an example in which wax is used as a temporary protective film as a method for dicing without fixing chips to the semiconductor substrate surface. That is, first, a semiconductor element or a minute device is formed on the main surface of the semiconductor substrate 1 by making full use of a semiconductor element process represented by photofabrication and a micromachining technique (A). Next, a resin or wax is applied to the main surface of the above-mentioned structure on which a semiconductor element or a micro device is formed, a protective film 2 made of the resin or wax is formed, and a mount tape 3 is attached to the back surface of the above-mentioned structure. (B). The structure is diced 4 with a diamond grindstone and divided into chips 5 (C). Next, the chip 5 is removed from the mount tape 3 by the pickup 6 (D). The removed chip 5 is placed in a cleaning tray 7 and washed with an organic solvent to remove the protective film 2 made of resin or wax (E).

However, in the above example in which the resin or wax is used as the temporary protective film, since the protective film made of the resin or wax is washed and removed with the organic solvent, the cleaning is performed after the chips are divided. There is a problem that it takes a lot of man-hours. In particular, in the case of a micro device having a cavity or a movable part, it is quite difficult to sufficiently wash and remove the resin and wax in the cavity, a large amount of organic solvent is required, and the removal is sufficient. There are not many non-destructive inspection methods. Further, it is difficult to improve the yield because the microdevice is damaged in the cleaning process or the periphery of the chip is hit and scratched. Therefore, this is a method that may increase the cost.

Next, as a microdevice having a cavity portion or a movable portion, "Transducers 1987 (The 4th Interna
tional Conference on Solid-State Sensor and Actua
[Tors) pp.336-339 ", the dicing method using resin or wax as a temporary protective film will be described in some detail with reference to FIG. Reference numeral 301 denotes a silicon substrate of a sensor chip, and an overlapping portion 303 and a diaphragm 304 are formed by anisotropic etching.The diaphragm 304 is opened to improve sensor sensitivity, and a so-called beam may be formed. , P
A fixed electrode 306 and a bonding pad 302 are formed on a glass substrate 305 using YREX7740. The silicon substrate 301 and the glass substrate 305 processed as described above are joined by anodic bonding.
The bottom surface of the weight portion 303 and the fixed electrode 306 face each other with a gap of at most 1 to several μm to form a capacitor, and the movement of the weight portion 303 due to acceleration is detected by the change of the capacitor (A). Although only the structure of one chip is shown in the drawing, many of them are actually formed on the substrate.

Resin or wax 307 is applied to the above structure by brushing or the like, and the chips are divided by dicing. At this time, the gap 308 is also filled with resin or wax, and the movable weight portion 303 is fixedly held to prevent damage due to dicing.
The chips of dicing are prevented from entering the inside of 08. The gap 308 is no more than 1 to several μm at the most. Therefore, even if only one grain of dicing chips penetrates into the gap 308, the movement of the weight portion 303 due to acceleration does not achieve the designed stroke, and the weight portion 303 Fixed electrode 3
Hit 06. In some cases, the weight section 303 and the fixed electrode 306 are electrically short-circuited, and the chip does not function as a sensor (B).

Next, the above dicing-divided chip is
Wash with an organic solvent such as acetone (C). At this time, the resin or wax 309 in the gap 308 is difficult to clean, and remains quite persistent. In order to improve the cleaning power, a method such as boiling with an organic solvent may be used, but boiling with an organic solvent that is flammable and explosive is extremely dangerous, and a dedicated device that takes measures against it is required. And Further, there is no suitable means for nondestructively knowing that the resin or wax 309 in the gap 308 has been removed. For example, when trying to confirm from a transmission image of some kind of energy ray, the glass substrate 30 made of glass is used.
5, the weight portion 303 made of silicon and the fixed electrode 306 made of metal are filtered,
Not to mention visible light, there is no usable energy ray including infrared rays and X-rays.

As a method of improving the conventional example shown in FIG. 13 using a resin or wax as a temporary protective film, there is a method disclosed in Japanese Patent Publication No. 23324/1990. In this case, instead of wax, an adhesive tape using a UV-curable glue is used as a temporary protective film.
4 (created according to Figure 13 and different from the original)
Will be described below. First, a semiconductor element or microdevice is formed on the main surface of the semiconductor substrate 1 by making full use of a semiconductor element process represented by photofabrication and a micromachining technique (A). Next, the adhesive tape 10 using an ultraviolet-curing adhesive is attached to the main surface of the above-mentioned structure on which the semiconductor elements or microdevices are formed, and the mount tape 3 is attached to the back surface of the above-mentioned structure (B). Next, the structure is diced 4 with a diamond grindstone to divide into chips 5 (C). Next, the adhesive tape 11 on the surface of the chip 5 of the above structure, which is made of an ultraviolet curable adhesive, is irradiated with ultraviolet rays to cure the adhesive (D). Next, the adhesive tape 11 on the surface of the chip 5 of the above-mentioned structure using the UV-curable sizing agent is replaced with another adhesive tape 1.
Remove by 2 (E). Finally, the chip 5 is removed from the mount tape 3 by the pickup 6 (F).

However, in the method of the above-mentioned conventional example in which an adhesive tape using a UV-curable glue is used as a temporary protective film, only the outermost surface is protected and the cavity and the movable part are protected. Since it has an essential defect that it cannot perform, it is difficult to apply it to a micro device having a cavity or a movable part. Further, since the sizing agent is attached to the surface on which the semiconductor element or the micro device is formed, there is a problem that the sizing agent remains on the surface. This is because the UV-curable adhesive agent does not lose its adhesive strength because it loses its adhesive strength when irradiated with ultraviolet light. There was a problem that it was peeled off. Further, in order to attach the adhesive tape, it is necessary to apply a certain amount of pressure to the tape, which causes a problem that the microdevice is damaged when the tape is attached. in this way,
It is difficult to apply a protection method that mechanically applies a force to a micro device both during protection and removal, to a micro device that is easily damaged.

In addition to the above-mentioned two dicing methods, a method for dicing and dividing a minute device with a high yield has not yet been developed. A protection method other than the one intended for temporary protection during dicing,
The applicability of these methods to dicing division of a micro device will be described below. For example, JP-A-63-41
As disclosed in Japanese Patent No. 855, in order to prevent dust from directly adhering to the mask substrate, a method of spin coating a solution of a sublimable substance on the mask substrate to temporarily form a protective film is known. is there. However, since this method uses the spin coating method, it needs not only a dedicated device but also has a problem that it is difficult to apply to a structure having a cavity portion or a movable portion due to a problem of breakage. That is, a so-called bulk micromachine that uses the bulk of a silicon substrate has a mechanical structure on the back surface, and the element is damaged even by a vacuum chuck during spin coating. Also, the thickness of the protective film that can be formed is thin,
Since it is from several thousand Å to several μm at the most, it is not enough to protect microdevices, and the holding time until the film of the sublimable substance sublimates and disappears is short, and it serves as a protective film during dicing. It's not a workable way.

Further, for example, as a method for holding the movable portion formed on the surface, there is a freeze-dry method (IE
EE 1991 pp.63-66). What is this freeze-dry method?
This is a method in which water or an organic solvent is applied to the movable part, the applied droplets are cooled and frozen, and the frozen droplets are sublimated under reduced pressure. This method is used, for example, in the step of drying a surface type micromachine to prevent the movable portion formed on the surface from being deformed or destroyed by the surface tension with the substrate.

The manufacturing of the micro device will be described below in some detail. FIG. 9 shows one of the basic structures of the micro device. Here, 200 is a microdevice made of polysilicon, 201 is a silicon substrate holding the microdevice 200, and 202 is a silicon substrate 201 for the microdevice 200.
A fixed part connected to the mobile device 203, a movable part of the microdevice 200,
Reference numeral 204 is a gap for making the movable portion of the micro device 200 movable. Various surface type micromachines are mainly constructed by combining these basic structures. next,
The basic manufacturing procedure of the microdevice shown in FIG. 9 will be described with reference to FIG. That is, first, an oxide film 205 as a sacrificial layer is formed on the main surface of the silicon substrate 201 by a method such as CVD (A). Next, the oxide film 20
An opening 206 is formed at a portion of No. 5 corresponding to the fixed portion where the microdevice 200 is connected to the silicon substrate 201 by photo / oxide film etching (B). Next, the above-mentioned structure is provided with polysilicon 2 which is a member constituting a micro device.
07 is formed by a method such as CVD (C). Next, the polysilicon 207 is formed into the shape of the microdevice 200 by photo dry etching (D). Next, the above structure is immersed in an oxide film etching solution 208 mainly containing hydrofluoric acid to etch the oxide film 205 as a sacrifice layer. By this step, the gap 204 that makes the movable part of the micro device movable is formed, and the movable part 203 of the micro device becomes movable (E). Next, the structure is immersed in pure water 209 and thoroughly washed. By this step, the oxide film etching solution 208 in the gap 204 is replaced with pure water (F). Conventionally, the above structure was dried as it was to obtain a microdevice. At this time, as the liquid pure water 209 evaporates and the volume decreases, the pure water 20
The movable portion 203 of the microdevice 200 is attracted to the silicon substrate 201 by the surface tension of 9 and finally becomes stuck (sticking). In this state,
The function as a microdevice can no longer be expressed (G).

The freeze-dry method is a drying method for preventing this sticking, which will be described with reference to FIG. 11A corresponds to FIG. 10F, and the pure water 209 is replaced with an organic solvent in some cases. Next, the above structure is pulled out from the tank and pure water is frozen without being dried to form ice 210 (B). Next, when the structure is vacuum dried, the solid ice 210 is sublimated and the microdevice 200 can be obtained without causing sticking (C). This is because what is in the gap 204 is not liquid water,
This is because the solid ice does not cause a pull-in phenomenon due to surface tension during evaporation. In this freeze-dry method, when a substance having a melting point near room temperature, for example, t-butyl alcohol (melting point 25.6 ° C.) is used, a melt can be obtained by simple heating. The movable part can be held. However, this freeze-dry method requires special equipment to control the temperature and pressure, and must be kept well below room temperature to prevent melting and high speed sublimation during the holding period. Further, since water and solids of t-butyl alcohol are soluble in water, they cannot be applied to a process such as a dicing process, a wet etching process, a cleaning process, or the like which comes into contact with water or an aqueous solution.

In view of such problems, the present inventors have considered
First, a solution of a sublimable substance is applied to the cavity or the movable part, and the cavity or the movable part is filled with the sublimable substance by heat treatment, and the sublimable substance is held stably for a desired period, and then it is easily completely removed. Inventing a method for easily and surely providing a temporary sealed and protected microdevice, and has already filed an application (Japanese Patent Application No. 6-145845).
Issue: unpublished). However, this method was an excellent method of selectively filling the sublimable substance only in the cavity or the movable part inside the outermost surface of the microdevice, so that the film coating the outermost surface of the microdevice was formed. It could not be formed.

[0014]

As described above, in the method of manufacturing a device having a microstructure, the conventional technique has various problems and problems. The object of the present invention is to solve the problems of the above-mentioned conventional techniques, to form a uniform, semi-transparent, long-holding protective film without damaging a microdevice, and to reduce the number of steps and capital investment. In addition, the cost is low, the risk of contamination is low, the protective film is easily and completely removed, does not require inspection, and provides a means for forming a temporary protective film with high yield and high productivity. When applied to the dicing process, the chip can be divided with a high yield, and when applied to the drying process after the sacrifice layer etching, for example, a microdevice without sticking is required without requiring a special device. It's easy to get.

[0015]

The above-mentioned object is to form a melt film of a solid sublimable substance at room temperature and normal pressure on one main surface on which the microstructure is formed in the manufacture of a device having the microstructure. Then, a manufacturing method including a step of cooling the melt coating to form a protective film having a structure having at least a solid phase, and thereafter vaporizing and removing the protective film, wherein the melt coating and the minute This can be achieved by providing a method of manufacturing a device having a microstructure, which is characterized by including a step of improving wettability with the structure. To summarize the above, a sublimable substance is used as a material for the temporary protective film, and a meltable material of the sublimable substance and a member having good wettability are arranged on the outer periphery of the region to be protected to cover the region to be protected. A temporary protective film is formed by forming a melt film of a sublimable substance and solidifying the melt film.

[0016]

In the present invention, the liquid is a melt of a sublimable substance or an organic solvent such as a naphthalene melt or isopropyl alcohol (hereinafter abbreviated as IPA), and the solid surface is a wettability between aluminum and an oxide film. Make use of the difference. The surface of the microdevice is composed of various members. When roughly classified, oxide film materials represented by PSG (phosphosilicate glass) films occupy the main position, and other aluminum films are represented. For example, wiring material. Here, for the sake of simplicity, the wettability will be described for the case where an aluminum film and an oxide film are used as the solid surface and IPA and melt naphthalene are used as the liquid.

In general, "wettability" is a degree of a phenomenon in which a liquid pushes a gas (atmosphere) away from a solid surface, and has the same meaning as wettability. (A brief explanation of the terms relating to wettability is given, for example, in the Chemical Dictionary (Kyoritsu Shuppan). For the phenomenon of wettability, see, for example, Basic Lectures on Physical Properties of Metals, Volume 10, Interface Physical Properties (Maruzen). Has been). This "wettability" of the liquid to the solid surface is
"Contact angle", that is, "at the contact point (P) of the three phases of solid, liquid, and gas, of the angle between the tangent line drawn to the liquid and the surface of the solid, whichever contains the liquid" A system with a small contact angle is said to have good wettability, and a system with a large contact angle is said to have poor wettability. The driving force for the phenomenon of wetting is a reduction in free energy of wetting represented by the difference (σ _s −σ _i ) between the solid-gas interface tension (σ _s ) and the solid-liquid interface tension (σ _i ). From the balance of tension in the direction of the solid surface at the contact points (P) of the three phases, there is a relationship of σ ₁ cos θ = σ _s −σ _i (Equation ₁ ) with the surface tension (σ ₁ ) of the liquid.

The contact angle (θ) is determined by the balance between the work (W _a ) of adhesion of a solid to a liquid per unit area and the work (W _c ) of aggregation of the liquid per unit area,

## EQU1 ## Therefore, in a system with good wettability, the cohesive force of the solid exceeds the cohesive force of the liquid, and the liquid rapidly spreads to the surface of the solid. The cohesive force of the liquid exceeds and the liquid does not spread to the surface of the solid but boils up.

As described above, since the surface of the microdevice is generally dominated by the oxide film type material, the melt of naphthalene (naphthalene which is melted by heating to become liquid) is used in the microdevice. Since the wettability with the region in which the micro device is formed is poor, and therefore the ball ups without expanding into a thin film, the region in which the micro device is formed cannot be coated with naphthalene as it is.
However, on the surface of aluminum, the melt of naphthalene expands into a thin film, so that it is possible to coat the area of aluminum with naphthalene. What should be noted is that one of the three (3) contact points of solid (region where microdevice is formed, aluminum region, oxide film region), liquid (naphthalene melt), and gas (atmosphere) The behavior of the liquid (naphthalene melt) as an aggregate is determined. In FIG. 1D of the embodiment described below, the reason why the naphthalene melt expands in the region where the microdevice is formed depends on the position of the contact point (actually a closed curve) of three phases of solid, liquid and gas. . If the contact point of the naphthalene melt is in the area where the micro device is formed or in the oxide film area around the wafer, the cohesive force of the naphthalene melt exceeds the adhesive force, so the naphthalene melt will coagulate and reduce the surface area. On the other hand, if the contact point of the naphthalene melt is in the aluminum region surrounding the region where the microdevice is formed, the adhesive force of the naphthalene melt exceeds the cohesive force, and therefore the naphthalene melt expands and becomes a solid. Try to wet the surface. As a result of these attacks, the contact point of the naphthalene melt is the outermost peripheral portion of the aluminum region surrounding the region where the microdevice is formed, and the innermost peripheral portion of the oxide film region surrounding the aluminum region, that is, The boundary between the aluminum region surrounding the formed region of the device and the oxide film region surrounding the aluminum region will be pinned. This state is a thermodynamically metastable state, and if a contact point of three phases of solid, liquid, and gas occurs in the region where the microdevice is formed, for example, from the cavity inside the microdevice. When air bubbles rise, the naphthalene melt quickly transitions to a torn and torn ball-up state.

In practice, for example, the amount of liquid of silicon wafer size shown in the following embodiment is not a minute droplet in which gravity can be ignored, and the main surface on which the minute device is formed is complicated by the minute device. Since there is a unique structure, so-called wetting and capillarity occur for the same coagulated liquid, and the pressure distribution inside the liquid and the stress of the members that compose the micro device are involved in a complicated manner. It's pretty hard to do.
Therefore, here, it is qualitatively summarized in Table 1 below.

[0022]

[Table 1]

In Table 1, for example, the wettability of the IPA system is qualitatively expressed as "good" and the contact angle is "small". More correctly, the contact angle (θ) is set to 0 and the solid-gas interface is set. The difference (σ _s −σ _i ) between the tension σ _s and the solid-liquid interfacial tension (σ _i ), that is, the adhesion tension should be used as a measure of wettability. Also,
Wetting of structures that can be regarded as capillaries among the structures of microdevices is said to be good if the solid-gas interface tension (σ _s ) exceeds the solid-liquid interface tension (σ _i ). However, the surface tension of the liquid itself does not matter so much, depending on the case, as the liquid soaks into the porous body and the liquid spontaneously gets wet.

[0024]

EXAMPLES The method for manufacturing a microdevice of the present invention will be specifically described below with reference to examples.

[0025]

EXAMPLE 1 A method for forming a solid film of a sublimable substance as a temporary protective film of the present invention will be described with reference to FIG. (A) First, the semiconductor substrate 100 on which a semiconductor element or a micro device is formed is heated. Even if the heating temperature is low, it is sufficient if it is equal to or higher than the melting point of the sublimable substance used, and it is possible to reach the boiling point of the substance. Here, 103 is a region in which a semiconductor element or a micro device is formed, 102 is an aluminum region surrounding the region 103 in which a semiconductor element or a micro device is formed, and 101 is an oxide film region surrounding the aluminum region 102.

(B) Next, a naphthalene melt solution 104 is formed by dropping a naphthalene melt solution on the main surface of the structure so as to cover the aluminum region 102. Note that the naphthalene melt and the semiconductor element or the region 103 in which a microdevice is formed have poor wettability, and when the amount of the naphthalene melt to be dropped is small, the semiconductor element or the semiconductor element or Although the naphthalene melt does not cover the region 103 where the microdevice is formed, when the amount of the dropped naphthalene melt reaches a certain level, the semiconductor substrate 1
A liquid film of size 00 is held by the surface tension.
Of course, if the amount is too large, the naphthalene melt will overflow from the semiconductor substrate 100. The optimum amount of the naphthalene melt to be dropped depends on the size of the semiconductor substrate 100 and the wettability between the naphthalene melt and the oxide film region 101.

(C) Next, the naphthalene melt layer 104 of the above structure is reduced by evaporation. It should be noted that the naphthalene melt has poor wettability with the oxide film, and the naphthalene melt layer 10 reaches the boundary between the oxide film region 101 and the aluminum region 102.
In No. 4, the bottom area is reduced while maintaining a large contact angle.

(D) Next, the naphthalene melt layer 104 of the above structure is further reduced by evaporation. The naphthalene melt has good wettability with aluminum, and the oxide film region 1
01 to the boundary between the aluminum region 102, the naphthalene melt layer 104 keeps a large contact angle, and reduces the bottom area.
The contact angle is reduced while keeping the outermost circumference of 2.

(E) Finally, the thickness of the liquid coating of the naphthalene melt layer 104 of the above structure is an appropriate thickness, for example 10
When the thickness is reduced to 0 μm, the structure is cooled to form the naphthalene melt layer 104 into a semitransparent naphthalene solid film 105 serving as a temporary protective film.

In the above example, the case where the aluminum region 102 surrounding the region 103 in which the semiconductor element or the micro device is formed is provided in the outer peripheral portion of the substrate 100 has been described. However, the present invention is not limited to this, and each chip is not limited to this. May be provided so as to surround them, or every several chips, or may be provided on a jig instead of being provided on the substrate 100. Further, the material is not limited to aluminum, and any material having good wettability may be used, and various metals can be used. The jig is not limited to one substrate, but may be a jig that simultaneously surrounds a plurality of substrates. In order to prevent the liquid containing the sublimable substance from entering the gap between the jig and the substrate by the capillary phenomenon, another liquid may be injected in advance. Further, the oxide film region 101 may be any member as long as it has a poor wettability with the naphthalene melt layer 104, Teflon resin can be used, and it may be provided on a jig instead of being provided on the substrate 100.

In the above example, the case where the naphthalene melt is dropped is described, but the invention is not limited to this.
A solution of naphthalene may be used. The solution of naphthalene need not be a solution at room temperature, but may be a heated concentrated solution having a saturated (room temperature) concentration or higher. Further, after the dropping, the solvent may be selectively evaporated and concentrated. Further, in the above-mentioned example, when the naphthalene melt layer 104 is formed, the case where the semiconductor substrate 100 is heated and then the naphthalene melt is dropped is described. It does not matter if it is sprayed and then heated to melt. Of course, the method is not limited to the spraying of powder, and the semiconductor substrate 100 may be electrostatically adhered and then heated and melted.

As a method for heating the semiconductor substrate 100, various methods other than heater heating can be used. Further, although naphthalene has been described as an example in the above example, it is not limited to this and may be any sublimable substance that is solid at room temperature and atmospheric pressure, such as p-dichlorobenzene, tetrachlorodifluoroethane, and in some cases. It can be camphor that is soluble in water. Further, in addition to using the sublimable substance alone, other components may be mixed, or a sublimable substance in which an organic solvent is mixed to cause a freezing point depression may be used. Also,
The temporary protective film does not have to be a complete solid film, and when viewed microscopically, the liquid phase may coexist in the porous solid phase.

The loss of the naphthalene melt layer 104 from the above (B) to (D) may be sucked by a dropper in addition to the loss by evaporation. In some cases,
It is also possible to drop as much naphthalene melt as necessary to form the film of (D) and expand it to the aluminum region 102 by acceleration or the like. The expansion of the liquid due to this acceleration has extremely poor wettability between the naphthalene melt and the region where the microdevice 103 is formed, and when the naphthalene melt is dropped,
It is also effective in the case where the naphthalene melt overflows from the substrate before forming the naphthalene melt layer 104 covering the entire main surface of the substrate 100 in (B). Further, the aluminum region 102 surrounding the region 103 in which the semiconductor element or the micro device is formed does not need to be completely continuous and may be formed in an island shape at a certain interval, for example. Further, the oxide film region 101 surrounding the aluminum region 102 does not have to be formed completely continuously, and may be formed in an island shape at a certain interval, for example.

Next, an example of the dicing procedure when the method of the present invention is used will be described with reference to FIG. (A) First, a semiconductor element process or a microdevice is formed on the main surface of the semiconductor substrate 1 by making full use of a semiconductor element process represented by photofabrication or a micromachining technique. (B) Next, a naphthalene solid film 105 as a temporary protective film is formed on the main surface of the above-described structure on which the semiconductor element or the minute device is formed by the method described in the drawings. (C) Next, the mount tape 3 is attached to the back surface of the structure. (D) Next, the structure is diced 4 with a diamond grindstone and divided into chips 5. (E) Finally, the chip 5 is removed from the mount tape 3 by the pickup 6.

The solid film of the sublimable substance on the chip can be easily and completely removed by leaving it alone, and no residue remains. If necessary, it can be rapidly removed under heating or reduced pressure conditions.

Next, a case where the method described with reference to FIG. 1 is applied to a surface type micromachine will be described with reference to FIG. 3 by taking an infrared sensor having a heat separation structure as an example. 3A to 3E are respectively shown in FIGS.
Corresponds to (E). (A) In FIG. 3, reference numeral 500 denotes a silicon substrate having an infrared sensor formed on its main surface, 501 denotes a silicon nitride film, 5
02 is a cavity 50 by alkali anisotropic etching
4 is an etching opening for forming 4 and 503 is a diaphragm of a thermally separated silicon nitride film. here,
A general diaphragm 503 has a size of about several tens to several hundreds of μm, and an etching opening 502 has a size of about several to several μm.
It is several tens of μm. Note that in reality, the diaphragm 503
Although a thermocouple, an infrared absorption part, etc. are formed on the upper part, they are omitted because they are not necessary for the description here.

(B) and (C) Naphthalene melt layer 1
When 04 is formed, the wettability between the naphthalene melt and the silicon or silicon nitride film, which is a member forming the infrared sensor, is poor.
Therefore, the naphthalene melt does not enter the cavity 504. (D) Even when the naphthalene melt layer 104 is thinned and the liquid film thickness becomes thin, the coating film spread in the region where the infrared sensor is formed is retained. This is because the aluminum region 102 having good wettability with the naphthalene melt is provided, and the naphthalene melt is expanded by this.
Aluminum region 102 having good wettability with the naphthalene melt
If is not provided, as in the case of heating and evaporating water in a frying pan, it will be shrunk and shrink in a ball-up state. (E) When the liquid coating of the naphthalene melt covers the region where the element is formed as in (D) above, the solid coating 10 of naphthalene as a temporary protective film is cooled when cooled.
5 is formed.

[0038]

[Embodiment 2] Next, the wettability between the naphthalene melt and the region in which the microdevice of 103 in FIG. 1 is formed is extremely poor, and when the naphthalene melt is dropped, as shown in FIG. An example in which the naphthalene melt overflows from the substrate before forming the naphthalene melt layer 104 covering the entire main surface of the substrate 100 will be described with reference to FIG. Note that such an example is, for example, a case where the main part of the surface constituting the microdevice is formed of a silicon oxide film.

(A) The semiconductor substrate 100 on which a semiconductor element or a micro device is formed is heated. (B) An appropriate amount of naphthalene melt is dropped onto the main surface of the structure to form a naphthalene melt island group 600. (C) The naphthalene melt island group 600 of the above structure is formed of a member having good wettability with the naphthalene melt, for example, the metal wire 6
01, the substrate 100 is scanned. (D) As a result, the naphthalene melt island group 600 of the structure is connected to form the naphthalene melt layer 104. (E) The naphthalene melt layer 104 of the above structure is reduced by evaporation. (F) When the thickness of the liquid coating of the naphthalene melt layer 104 of the above structure is reduced to an appropriate thickness, for example, 100 μm, the structure is cooled and the naphthalene melt layer 104 is translucent. The film 105 is formed. The above method can be applied even when the naphthalene solid coating 105 can be formed by the method shown in FIG. 1, and since a naphthalene melt having a volume of about the naphthalene solid coating 105 may be dropped, it is possible to perform the evaporation / reduction process. The time required can be extremely shortened.

As described above, in the embodiment shown in FIGS. 1 and 4,
As described in FIG. 3, it is not a method of filling the inside of the cavity with the sublimable substance. In a microdevice or a manufacturing process to which the method of the present invention is applied, in some cases, there is a need not only to protect the surface by coating but also to fill the inside of the cavity with a sublimable substance. Such an example occurs, for example, when a dicing saw cuts across a cavity.

[0041]

[Embodiment 3] An embodiment which meets the above needs will be described with reference to FIGS. Note that FIG. 5 and FIG.
In (A) to (F), each corresponds to the same step. (A) First, the semiconductor substrate 100 on which a semiconductor element or a micro device is formed is heated. In this case, the heating temperature is
It is preferably above the melting point of naphthalene and below the boiling point of IPA. Incidentally, 101 is an oxide film region, and 102 is an aluminum region. (B) An appropriate amount of IPA (isopropyl alcohol) is dropped on the main surface of the structure to form an IPA liquid coating 700. Since IPA has good wettability with the material forming the device, it penetrates into the cavity 504 through the opening 502 for etching, so that the air in the cavity 504 is replaced with IPA. At this time, aluminum region 1
If there is no oxide film region 101 surrounding 02, IPA has extremely good wettability with respect to aluminum.
No. 00 flowing out from the upper surface and the IPA liquid coating 700 cannot be formed. (C) The naphthalene melt is dropped onto the structure to form a naphthalene melt layer 104. At this time, the dropped naphthalene melt and the IPA liquid coating 700 mutually dissolve.
The IPA in the cavity 504 and the naphthalene melt are mutually diffused, and the IPA in the cavity 504 is replaced by the naphthalene melt. (D) and (E) Naphthalene melt layer 1 of the above structure
04 is depleted by evaporation. At this time, the evaporation of IPA takes precedence over the evaporation of naphthalene, and the IPA concentration in the naphthalene melt layer 104 and the IPA concentration in the cavity 504 decrease. (F) When the thickness of the liquid coating of the naphthalene melt layer 104 of the above structure is reduced to an appropriate thickness, for example, 100 μm, the structure is cooled and the naphthalene melt layer 104 is translucent. The coating 105 is used. At this time, the naphthalene melt in the cavity 504 also solidifies.

In the above description, the case where IPA is used has been described as an example, but the present invention is not limited to this, and any solvent that dissolves the sublimable substance to be used and has a good wettability with the material forming the microdevice can be used. In addition to IPA, any of methanol, ethanol, acetone, benzene and the like can be used. Further, the solvent may be used alone, or may be a mixed solvent or a solvent in which a sublimable substance is dissolved.

Next, the pattern shape of the aluminum region surrounding the region where the microdevice is formed in the above embodiment will be described with reference to FIG. In FIG.
(A) is a substrate 100 on which the microdevice in FIG. 1 is formed.
In a view of the main surface of the chip 901 from above, the area where the chips 901 are gathered is the area 103 in which the microdevice is formed in FIG. 1, and the aluminum area 102 surrounding the area is the four areas of the chip 901. It is formed by arranging a solid pattern 902 of aluminum which is one-half the size. When the naphthalene solid film 105 is formed on the structure of FIG. 7A by the method described in FIGS.
As shown in (B), the naphthalene solid film 105 is formed in the outermost peripheral shape of the aluminum region 102.

In this example, the aluminum region 102 has a corner. 1 (D), 4 (E), and 5 (E), the naphthalene melt layer 104 has a small contact angle,
The place where the surface tension is about to squeeze is held by the aluminum, which has a slightly better wettability. When the aluminum region 102 has a corner portion, the naphthalene melt layer 104 at the corner portion becomes
2 to the inside of the boundary between the oxide film region 101 and the oxide film region 101, that is, to the region 103 side where the micro device is formed. When the chip 901 is extremely small, the drawn amount may be larger than the diagonal line of the solid pattern 902. In such a case, as soon as the boundary line between the naphthalene melt layer 104, the surface of the substrate 100 and the atmosphere is drawn to the corner of the region where the microdevice is formed,
The naphthalene melt layer 104 can no longer exist as a film and changes into a water-like island shape on the frying pan,
Therefore, the naphthalene solid film cannot be formed.

FIG. 8 shows an aluminum region pattern in which such a problem does not occur. Here, the outermost peripheral shape of the aluminum region is a circular pattern 903, which is a shape having no corners. Of course, in addition to the circular pattern, an ellipse may be used as long as it is composed of a gentle curve.

[0046]

[Embodiment 4] In this embodiment, the application of the method of the present invention to the drying step after the sacrifice layer etching, not to the dicing step, will be described with reference to FIG. (A) In the same manner as in FIG.
Immerse in 9. (B) Next, the above structure is immersed in an IPA bath, and the pure water 209 is replaced with IPA211. (C) The above structure is dipped in a naphthalene melt bath to obtain an IP
After substituting A211 with the naphthalene melt, the naphthalene melt is solidified by pulling out from the naphthalene melt bath to form the naphthalene solid coating 212.

(D) By leaving the above structure alone, the solid naphthalene sublimes, and the microdevice 200 can be obtained without sticking. This is because the substance substituted in the gap 204 is solid naphthalene, not liquid water, so that the drawing phenomenon due to the surface tension does not occur during evaporation.

If the sacrifice layer etching process is performed immediately before the chip dividing process by dicing in the above embodiment, dicing may be performed in the state of FIG. 12C, and the sticking prevention measure and the dicing protection measure are simultaneously performed. Can be performed, and the total process can be greatly simplified.

In the above embodiment, IPA is used as the solvent.
In the above, an example in which naphthalene is used as the sublimable substance has been described, but the solvent is not limited to this, and any solvent may be used as long as it dissolves water and naphthalene. ,ethanol,
Acetone or the like can be used, and the solvent may be used alone, or may be a mixed solvent, for example, a solvent in which a sublimable substance is dissolved. Further, the sublimable substance may be any solid sublimable substance at room temperature and normal pressure, and for example, camphor which is soluble in water may be used if used as a drying method in the sacrifice layer etching step. .

Although the embodiments of the present invention have been described mainly using the sensor formed on the semiconductor substrate as an example, the present invention is not limited to this. For example, a glass substrate or a metal substrate may be used. Can be applied not only to the substrate but also to the main surface of the structure. Of course, it is not necessary to form a minute device, and the invention can be applied to various processes requiring a temporary protective film for a device or a component having a minute structure.

[0051]

As described above, by adopting the method of manufacturing a micro device as the method of the present invention, the problems of the prior art can be solved, and the micro device can be made uniform without being damaged. It is possible to form a temporary protective film that is translucent and has a long holding time. And according to the method of the present invention, the number of steps is small, the capital investment and the cost are low, the risk of contamination is small, the protective film is easily and completely removed, and inspection is unnecessary,
Moreover, it is characterized by high yield and excellent productivity. Therefore, if it is used in a dicing process for a micro device, for example, it is possible to divide a chip with high yield. Also, for example, if used in the drying step after etching the sacrificial tank,
It is possible to easily obtain a micro device without sticking without requiring a special device.

[Brief description of drawings]

FIG. 1 is a process diagram showing a method (No. 1) of forming a temporary protective film by a solid film of a sublimable substance according to the present invention.

FIG. 2 is a process drawing showing a dicing method using a solid film of a sublimable substance as a temporary protective film according to the present invention.

FIG. 3 is a process diagram showing an example of application of the method for forming a solid film of a sublimable substance (first) of the present invention to an infrared sensor.

FIG. 4 is a process diagram showing a method (No. 2) of forming a temporary protective film by a solid film of a sublimable substance according to the present invention.

FIG. 5 is a process drawing showing a method (No. 3) of forming a temporary protective film by a solid film of a sublimable substance according to the present invention.

FIG. 6 is a process diagram showing an example of application of the method for forming a temporary protective film by a solid film of a sublimable substance (part 3) of the present invention to an infrared sensor.

FIG. 7 is a pattern of a protective film formed by a method for forming a temporary protective film with a solid film of a sublimable substance according to the present invention (part 1).
FIG.

FIG. 8 is a pattern of a protective film formed by a method for forming a temporary protective film with a solid film of a sublimable substance according to the present invention (part 2).
FIG.

FIG. 9 is a diagram showing a basic structure of a micro device.

FIG. 10 is a diagram showing a method for manufacturing a microdevice.

FIG. 11 is a diagram for explaining a freeze-dry method.

FIG. 12 is a view for explaining the drying method of the present invention.

FIG. 13 is a process diagram showing a first example of a conventional manufacturing method, and a diagram showing a dicing method using a resin or wax as a temporary protective film.

FIG. 14 is a process diagram showing a second example of a conventional manufacturing method, and is a diagram showing a dicing method using an adhesive tape using an ultraviolet curing type sizing agent as a temporary protective film.

FIG. 15 is a process diagram showing a third example of a conventional manufacturing method, and a diagram showing application of a dicing method using a resin or wax as a temporary protective film to a micromachine.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Semiconductor substrate 2 ... Protective film made of resin or wax 3 ... Mount tape 4 ... Dicing groove 5 ... Chip 6 ... Pickup 7 ... Cleaning tray 10 ... Adhesive tape using UV curable glue 11 ... UV light on chip surface Adhesive tape 12 using a curable adhesive agent ... Adhesive tape 100 ... Semiconductor substrate on which microdevice is formed 101 ... Oxide film region 102 surrounding aluminum region surrounding the region where microdevice is formed ... Aluminum region surrounding element region 103 ... Area where microdevice is formed 104 ... Naphthalene melt layer 105 ... Naphthalene solid film 200 ... Microdevice 201 ... Silicon substrate 202 ... Fixed part 203 ... Movable part 204 ... Gap 205 ... Oxide film 206 ... Opening 207 ... Poly Silicon film 208 ... Oxide film etching liquid 209 ... Pure water 21 ... Ice 211 ... IPA 211 ... Naphthalene solid film 301 ... Sensor chip silicon substrate 302 ... Bonding pad 303 ... Weight part 304 ... Diaphragm 305 ... Glass substrate 306 ... Fixed electrode 307 ... Resin or wax 308 ... Gap 309 ... Gap 308 inside Resin or wax 500 ... Silicon substrate 501 on the main surface of which an infrared sensor is formed ... Silicon nitride film 502 ... Cavity 5 by alkali anisotropic etching
Etching opening 503 for forming 04 ... Diaphragm 504 of thermally-isolated silicon nitride film ... Cavity 600 ... Naphthalene melt island group 601 ... Wire 700 ... IP
A liquid coating 901 ... Chip 902 ... Solid pattern 903 ... Round pattern.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location H01L 21/78 LP

Claims (12)

[Claims] 1. In manufacturing a device having a microstructure, a melt film of a solid sublimable substance is formed on one main surface on which the microstructure is formed at room temperature and normal pressure, and then the melt film is formed. A manufacturing method including a step of cooling to form a protective film having a structure having at least a solid phase, and then vaporizing and removing the protective film, which improves wettability between the melt coating and the microstructure. A method for manufacturing a device having a microstructure, which comprises the steps of: 2. The step of improving the wettability between the sublimable substance melt coating film and the microdevice is a step of providing a member having good wettability with the sublimable substance melt in the vicinity of the microstructure. A method for manufacturing a device having a microstructure according to claim 1. 3. The step of improving the wettability between the sublimable substance melt coating film and the microdevice is such that at least one main surface on which the microstructure is formed is soluble in the sublimable substance. The method for manufacturing a device having a microstructure according to claim 1, further comprising the step of wetting with a liquid containing a solvent having good wettability with the microstructure. 4. The step of forming a melt coating film of the sublimable substance comprises at least a step of heating at least one main surface on which the microdevice is formed to a melting point of the sublimable substance or more. A method of manufacturing a device having the microstructure according to claim 2 or 3. 5. The step of heating above the melting point of the sublimable substance above the boiling point of a solvent which is soluble in the sublimable substance and has good wettability with the microstructure. A method for manufacturing a device having a microstructure according to claim 3 or 4, wherein: 6. The step of improving the wettability between the melt coating and the microdevice is a step of providing a member having good wettability with the melt of the sublimable substance on one main surface on which the microstructure is formed. The method for manufacturing a device having a microstructure according to claim 2, wherein: 7. The sublimable substance melt coating and a member having good wettability are so-called jigs and are provided in a device other than the device in which the microstructure is formed. A method for manufacturing a device having the described microstructure. 8. The closed curve of the three-phase boundary between the sublimable substance melt coating film, a member (solid) having good wettability with the sublimable substance melt coating film, and a gas is a shape having no corners. The method for manufacturing a device having a microstructure according to claim 2, wherein. 9. The sublimable substance melt coating film forming step comprises forming a liquid containing the sublimable substance into at least the microdevice by a jig formed of a member having good wettability with the melt coating film. 3. The method for manufacturing a device having a microstructure according to claim 2, further comprising the step of expanding on one main surface. 10. A member having poor wettability with the melt of the sublimable substance is provided in a region provided near the microstructure and surrounding the member having good wettability with the sublimable substance. Item 3. A method of manufacturing a device having a microstructure according to Item 2. 11. An apparatus having a microstructure according to claim 10, wherein the melt coating of the sublimable substance and the member having poor wettability are provided on one main surface on which the microstructure is formed. Manufacturing method. 12. A melt coating of a sublimable substance and a member having poor wettability are so-called jigs and are provided in a device other than the device having the microstructure. A method for manufacturing a device having a microstructure.