JP2008116366A - Surface shape sensor and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fingerprint sensor and its manufacturing method hardly causing deterioration in a passivation film even after long-term use. <P>SOLUTION: The surface shape sensor includes: a silicon substrate 10; an interlayer insulating film 40 formed above the silicon substrate 10; a detection electrode film 44a and a ground electrode film 44b formed on the interlayer insulating film 40 at an interval each other; a protection insulating film 51 formed on each of the interlayer insulating film 40, the detection electrode film 44a, and the ground electrode film 44b and having an opening 51a for exposing the ground electrode film 44b; and the passivation film 55 formed on the protection insulating film 51 and including a window 55a overlapping with the detection electrode film 44a and the opening 51a. An opening edge of the window 55a is chamfered. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a surface shape sensor and a manufacturing method thereof.

  In recent years, with the progress of the information society, biometric authentication technology for verifying identity based on individual physical characteristics has been put into practical use as security technology for preventing unauthorized use of bank cards and electronic money. Some biometric authentication techniques use palm veins and voiceprints, but fingerprint authentication techniques that use fingerprints have been extensively studied.

  For example, in Patent Document 1, light is applied to a fingerprint, and the fingerprint is optically collated from the reflected light.

  And in patent document 2, the pressure difference which arises with the unevenness | corrugation of a fingerprint is read with a piezoelectric thin film, and collation is performed.

  Moreover, in patent document 3, collation is performed based on the resistance change or capacity | capacitance change of a pressure sensitive sheet which arises by contact with skin.

  However, among these techniques, the technique of Patent Document 1 using an optical technique has a problem that it is difficult to reduce the size and cannot be used for general purposes, and uses are limited. Further, the technique of Patent Document 3 using a pressure-sensitive sheet is difficult to put into practical use because the material of the pressure-sensitive sheet is special and the processing of the pressure-sensitive sheet is also difficult.

  As a technique for solving these problems, Patent Document 4 discloses a capacitive fingerprint sensor (surface shape sensor) formed on a semiconductor substrate. In the fingerprint sensor, a plurality of detection electrode films formed in an array on a semiconductor substrate and the skin face each other, and each detection electrode film and the skin function as an electrode of a capacitor. The distance between the electrodes in the capacitor varies depending on the unevenness of the fingerprint. Therefore, a fingerprint image is obtained by causing each detection electrode film to function as one pixel and sensing and visualizing the capacitance of each capacitor. This type of fingerprint sensor does not require a special interface as compared with the optical type and can be miniaturized.

  In such a capacitive fingerprint sensor, it is necessary to form a passivation film functioning as a buffer material on the uppermost layer so that the circuit is not destroyed by contact with the finger. Further, in order to prevent the element from being deteriorated by moisture, a protective insulating film for blocking external moisture may be formed on the fingerprint sensor.

  For example, in Patent Documents 4 and 5, a silicon nitride film is formed as such a passivation film or a protective insulating film.

  On the other hand, in Patent Document 6, a laminated film of a silicon oxide film and a silicon nitride film is formed as a passivation film.

  When peeling of the passivation film or the protective insulating film disclosed in Patent Documents 4 to 6 occurs due to the use of the fingerprint sensor for a long period of time, moisture or the like enters the lower layer, and the reliability of the element is lowered. In addition, if the passivation film is formed in a structure in which oils and fats of the hand are easily attached, the capacitance between the detection electrode film and the skin varies due to the oils and fats, and the fingerprint cannot be recognized correctly.

Thus, in a fingerprint sensor that is touched directly by a finger, durability superior to that of a normal semiconductor device is required for the passivation film and the protective insulating film.
JP-A-61-218883 JP-A-5-61965 JP 7-168930 A JP 2003-269907 A JP 2000-194825 A Japanese translation of PCT publication No. 2002-520841

  An object of the present invention is to provide a fingerprint sensor in which a passivation film hardly deteriorates even after long-term use, and a method for manufacturing the same.

  According to an aspect of the present invention, a semiconductor substrate, an interlayer insulating film formed over the semiconductor substrate, and a detection electrode film and a ground electrode film formed on the interlayer insulating film at intervals from each other A protective insulating film formed on each of the interlayer insulating film, the detection electrode film, and the ground electrode film, and having an opening through which the ground electrode film is exposed; and the protective insulating film formed on the protective insulating film; There is provided a surface shape sensor having an electrode film and a passivation film having a window overlapping with the opening, wherein the opening end of the window is chamfered.

  According to another aspect of the present invention, a step of forming an interlayer insulating film above the semiconductor substrate, and a detection electrode film and a ground electrode film are formed on the interlayer insulating film at a distance from each other. Forming a protective insulating film on each of the interlayer insulating film, the detection electrode film, and the ground electrode film; and forming an opening in the protective insulating film through which the ground electrode film is exposed; There is provided a method for manufacturing a surface shape sensor, comprising: forming a passivation film having a window overlapping the detection electrode film and the opening on the protective insulating film; and chamfering the opening end of the window. .

  Next, the operation of the present invention will be described.

  In the present invention, in order to prevent the circuit from being destroyed by static electricity stored in a subject such as a finger, the ground electrode film is formed at a distance from the detection electrode film. The ground electrode film is exposed from the opening of the protective insulating film and the window of the passivation film. According to the present invention, since the opening end of the window is chamfered, the friction between the subject and the passivation film is reduced, and it is possible to prevent the film from peeling off the passivation film due to the friction with the subject.

  Such chamfering may be performed on the opening end of the opening of the protective insulating film. By doing so, friction between the protective insulating film exposed from the window of the passivation film and the subject is reduced, and peeling of the protective insulating film can be prevented.

  According to the present invention, since the opening end of the window of the passivation film is chamfered, the specimen can move smoothly on the passivation film, and the passivation film can be prevented from peeling off due to friction with the specimen. A highly reliable surface shape sensor that can withstand use can be provided.

  Hereinafter, a capacitive surface shape sensor according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

(1) 1st Embodiment FIGS. 1-19 is sectional drawing in the middle of manufacture of the sweep type surface shape sensor (fingerprint sensor) which concerns on this embodiment. In the following, a sensor region I for recognizing a fingerprint and a pad region II to which a bonding wire is bonded at the time of packaging are shown together in these drawings.

  First, steps required until a sectional structure shown in FIG.

  First, an element isolation insulating film 11 is formed by thermally oxidizing the surface of an n-type or p-type silicon (semiconductor) substrate 10, and the element isolation insulating film 11 defines an active region of the transistor. The height from the surface of the silicon substrate 10 to the upper surface of the element isolation insulating film 11 is about 200 nm. Such an element isolation structure is called LOCOS (Local Oxidation of Silicon), but STI (Shallow Trench Isolation) may be adopted instead.

  Next, after p-type impurities such as boron are introduced into the active region of the silicon substrate 10 to form the first and second p-wells 12 and 13, the surface of the active region is thermally oxidized to form the gate insulating film 14 and The resulting thermal oxide film is formed to a thickness of about 6 to 7 nm.

  Subsequently, an amorphous silicon film having a thickness of about 50 nm and a tungsten silicide film having a thickness of about 150 nm are sequentially formed on the entire upper surface of the silicon substrate 10. Note that a polycrystalline silicon film may be formed instead of the amorphous silicon film. Thereafter, these films are patterned by photolithography to form the gate electrode 15 on the silicon substrate 10 and the wiring 16 on the element isolation insulating film 11.

  Further, phosphorus is introduced as an n-type impurity into the silicon substrate 10 beside the gate electrode 15 by ion implantation using the gate electrode 15 as a mask, thereby forming first to third source / drain extensions 17a to 17c.

  Thereafter, an insulating film is formed on the entire upper surface of the silicon substrate 10, and the insulating film is etched back to be left as an insulating spacer 18 beside the gate electrode 15 and the wiring 16. As the insulating film, a silicon oxide film is formed by, for example, a CVD (Chemical Vapor Deposition) method.

  Subsequently, n-type impurities such as arsenic are ion-implanted again into the silicon substrate 10 while using the insulating spacer 18 and the gate electrode 15 as a mask, so that the first to first silicon substrates 10 on the side of the gate electrode 15 are first to first. Three source / drain regions 19a to 19c are formed.

  Further, a refractory metal film such as a cobalt film is formed on the entire upper surface of the silicon substrate 10 by sputtering. Then, by heating the refractory metal film to react with silicon, a refractory silicide layer 20 such as a cobalt silicide layer is formed on the silicon substrate 10 in the first to third source / drain regions 19a to 19c, The resistance of each source / drain region 19a-19c is reduced.

  Such a refractory metal silicide layer is also formed on the surface layer of the silicon substrate 10 where the element isolation insulating film 11 is not formed.

  Thereafter, the refractory metal layer which has not reacted on the element isolation insulating film 11 or the like is removed by wet etching.

Through the steps so far, the active region of the silicon substrate 10 includes the gate insulating film 14, the gate electrode 15, the first to third source / drain regions 19a to 19c, and the first to third MOS transistors TR _1. ~ TR ₃ is formed.

  Next, as shown in FIG. 1B, a silicon oxynitride (SiON) film having a thickness of about 200 nm is formed on the entire upper surface of the silicon substrate 10 by plasma CVD, and this silicon oxynitride film is formed as a cover insulating film. 21.

  Subsequently, a silicon oxide film having a thickness of about 1000 nm is formed on the cover insulating film 21 as the first insulating film 22 by a plasma CVD method using TEOS (tetra ethoxy silane) gas. Thereafter, the upper surface of the first insulating film 22 is planarized by polishing the first insulating film 22 by about 200 nm by a CMP method (Chemical Mechanical Polishing).

  In the present embodiment, the cover insulating film 21 and the first insulating film 22 thus formed constitute a first interlayer insulating film 23.

  Subsequently, as shown in FIG. 2A, a first resist pattern 24 having windows 24a to 24e is formed by applying a photoresist on the first interlayer insulating film 23, exposing and developing the photoresist. Form.

  Then, the first interlayer insulating film 23 is dry-etched using the first resist pattern 24 as a mask, thereby forming first to fifth contact holes 23a to 23e as shown in the drawing.

  Thereafter, the first resist pattern 24 is removed, and activation annealing is performed on the impurities in the first to third source / drain regions 19a to 19c. The activation annealing is performed, for example, by RTA (Rapid Thermal Anneal) with a processing time of 30 seconds in a nitrogen atmosphere.

  Next, steps required until a sectional structure shown in FIG.

  First, a titanium (Ti) film having a thickness of about 20 nm and a titanium nitride having a thickness of about 50 nm (as a glue film) are formed on the inner surfaces of the first to fifth contact holes 23a to 23e and the upper surface of the first interlayer insulating film 23 by sputtering. TiN) film is formed in this order.

  Next, a tungsten film is formed on the glue film by a CVD method, and the first to fifth contact holes 23a to 23e are completely buried with the tungsten film. The tungsten film has a thickness of 700 nm on the first interlayer insulating film 23, for example.

  Then, the excessive glue film and tungsten film on the first interlayer insulating film 23 are polished by the CMP method, and these films are first to fifth conductive in the first to fifth contact holes 23a to 23e. Leave as plugs 25a-25e.

  Subsequently, as shown in FIG. 3A, a first metal stacked film 26 is formed on the upper surfaces of the first to fifth conductive plugs 25 a to 25 e and the first interlayer insulating film 23. The metal laminated film is formed by sputtering, and is formed by forming a copper-containing aluminum film having a thickness of about 500 nm, a titanium film having a thickness of about 5 nm, and a titanium nitride film having a thickness of about 150 nm in order from the bottom.

  Thereafter, a photoresist is applied on the first metal laminated film 26, and is exposed and developed to form a second resist pattern 27.

  Next, as shown in FIG. 3B, the first metal wiring layer 26a is formed by dry etching the first metal laminated film 26 using the second resist pattern 27 as a mask. After the etching is finished, the second resist pattern 26 is removed.

  Next, steps required until a sectional structure shown in FIG.

  First, a silicon oxide film is formed to a thickness of about 2200 nm on the entire upper surface of the silicon substrate 10 by plasma CVD using TEOS gas, and this silicon oxide film is used as the second insulating film 28.

  Although not particularly illustrated, in the second insulating film 28 formed using the TEOS gas, “su” is easily formed between the adjacent first-layer metal wirings 26a. If the “su” remains formed, moisture and impurities remain in the “su”, and stress migration is likely to occur in the wiring 26a.

  Therefore, after the second insulating film 28 is formed, the upper surface of the second insulating film 28 is polished by the CMP method to expose “su” on the surface of the second insulating film 28. The amount of CMP polishing is typically about 1000 nm.

  Thereafter, a silicon oxide film having a thickness of 100 nm is formed as a first cap insulating film 29 on the upper surface of the second insulating film 28 by the plasma CVD method using TEOS gas again. Fill completely.

  The first cap insulating film 29 and the second insulating film 28 below form a second interlayer insulating film 30.

  Subsequently, as shown in FIG. 5, a third resist pattern 32 is formed on the second interlayer insulating film 30. Then, the second interlayer insulating film 30 is dry-etched through the window 32a of the third resist pattern 32, thereby forming the first hole 30a having a depth reaching the first metal wiring 26a.

  Thereafter, the third resist pattern 32 is removed.

  Next, steps required until a sectional structure shown in FIG.

  First, a titanium nitride film having a thickness of about 50 nm is formed as a glue film on the inner surface of the first hole 32a and the upper surface of the second interlayer insulating film 30 by sputtering.

  Next, a tungsten film having a thickness of about 700 nm is formed on the glue film by a CVD method, and the first hole 30a is completely filled with the tungsten film.

  Then, the excessive glue film and tungsten film on the second interlayer insulating film 30 are polished by the CMP method, and these films are left as the sixth conductive plug 34 in the first hole 30a.

  Subsequently, as shown in FIG. 7, a copper-containing aluminum film and a titanium nitride film are formed in this order on each of the second interlayer insulating film 30 and the sixth conductive plug 34 by sputtering. Is a second metal laminated film 35. The thickness of the second metal laminated film 35 is not limited, but the thickness of the copper-containing aluminum is about 500 nm, and the thickness of the titanium nitride film is about 120 nm.

  Thereafter, a fourth resist pattern 36 is formed on the second metal laminated film 35.

  Next, as shown in FIG. 8, the second metal multilayer film 35 is dry-etched using the fourth resist pattern 36 as a mask, and the second metal multilayer film 35 remaining without being etched is subjected to the second-layer metal wiring 35a and the bonding pad. 35b.

  Thereafter, the fourth resist pattern 36 is removed.

  Next, steps required until a sectional structure shown in FIG.

  First, a silicon oxide film having a thickness of about 400 nm is formed on each of the second-layer metal wiring 35a and the second interlayer insulating film 30 by plasma CVD using TEOS gas, and this silicon oxide film is formed as a cover insulating film. 37.

  The cover insulating film 37 has irregularities on the surface reflecting the second-layer metal wiring 35a. Therefore, in the next step, a silicon oxide film is formed as the third insulating film 38 on the cover insulating film 37 in order to embed this unevenness.

  In the present embodiment, SOG (Spin On Glass) excellent in embeddability is adopted as a method of forming the third insulating film 38, and the thickness of the third insulating film 38 on the flat surface of the cover insulating film 37 is about Set to 500 nm.

  Thereafter, a silicon oxide film having a thickness of about 1300 nm is formed as the sacrificial insulating film 39 on the third insulating film 38 by using a plasma CVD method using TEOS gas.

  A third interlayer insulating film 40 is configured by the insulating films 37 to 39 formed in this way.

  Even if the third insulating film 38 is formed of SOG having good embedding properties as described above, slight irregularities reflecting the second-layer metal wiring 35 a remain on the surface of the third interlayer insulating film 40.

  Therefore, next, as shown in FIG. 10, the upper surface of the sacrificial insulating film 39 is polished and planarized by the CMP method.

  Next, as shown in FIG. 11, a fifth resist pattern 43 is formed on the third interlayer insulating film 40.

  Then, the third interlayer insulating film 40 is dry-etched through the windows 43a and 43b of the fifth resist pattern 43, thereby forming second and third holes 40a and 40b on the second-layer metal wiring 35a.

Thereafter, the fifth resist pattern 43 is removed, and the third interlayer insulating film 40 is annealed in an N ₂ atmosphere to release moisture contained in the third interlayer insulating film 40 from the holes 40a and 40b. This annealing is performed, for example, at a substrate temperature of 430 ° C. for about 30 minutes.

  Next, as shown in FIG. 12, a titanium nitride film is formed as a conductive film 44 to a thickness of about 200 nm on the upper surface of the third interlayer insulating film 40 and the inner surfaces of the second and third holes 40a and 40b by sputtering. .

  The conductive film 44 is not limited to a titanium nitride film, and may be a titanium film or a titanium aluminum nitride film. As will be described later, the conductive film 44 serves as a detection electrode film close to the finger, and the corrosion resistance of the detection electrode film is improved by forming the conductive film 44 with a material containing titanium as described above. It is done.

  Further, even if the conductive film 44 is made of a noble metal such as Au, Ag, Pt, Pd, Rh, Ir, Ru, and Os, a detection electrode film having high corrosion resistance can be obtained.

  Here, before the conductive film 44 is formed, the third interlayer insulating film 40 is annealed to sufficiently release the moisture in the film from the holes 40a and 40b. Therefore, when forming the conductive film 44, the holes 40a and 40b are formed. Degassing out of the hole 40 is reduced, and it is possible to prevent the conductive film 44 from being formed in the holes 40a and 40b.

  Next, as shown in FIG. 13, a photoresist is applied on the conductive film 44, and is exposed and developed to form a sixth resist pattern 46.

  Subsequently, as shown in FIG. 14, the conductive film 44 is detected only in and around the second and third holes 40a and 40b by dry etching the conductive film 44 using the sixth resist pattern 46 as a mask. The electrode film 44a and the ground electrode film 44b are left.

  The electrode films 44a and 44b are formed at a distance from each other, and are electrically connected to the second-layer metal wiring 35a through the second and third holes 40a and 40b, respectively. The ground electrode film 44b is electrically connected to the silicon substrate 10 at the ground potential.

  Thereafter, the sixth resist pattern 46 is removed.

  Next, as shown in FIG. 15, a seventh resist pattern 48 is formed on the entire upper surface of the silicon substrate 10.

  Then, by etching the third interlayer insulating film 40 through the window 48a of the seventh resist pattern 48, an electrode lead window 40b is formed on the bonding pad 35b.

  After the etching is finished, the seventh resist pattern 48 is removed.

  Subsequently, as shown in FIG. 16, a silicon oxide film is formed to a thickness of about 100 nm on each of the third interlayer insulating film 40 and the electrode films 44 a and 44 b, and this silicon oxide film is used as the cover insulating film 50. . The cover insulating film 50 is formed by, for example, a plasma CVD method using TEOS gas.

  Here, when external moisture enters the surface shape sensor under actual use, water touches the first-layer metal wiring 26a and the second-layer metal wiring 35a in a state where the circuit operates and generates heat, and these wirings are touched. Stress migration occurs, and in the worst case, inconvenience such as disconnection of wiring occurs.

  Therefore, in the next step, a silicon nitride film having a thickness of about 1000 nm is formed on the cover insulating film 50 as a protective insulating film 51 that blocks moisture by plasma CVD. As a film forming gas for the silicon nitride film, a mixed gas of ammonia and silane is used. The film forming temperature is 400 ° C., high frequency power having a frequency of 13.56 MHz and power of 600 W and high frequency power having a frequency of 400 kHz and power of 200 W are applied to the film forming atmosphere.

  A silicon nitride film is suitable as the protective insulating film 51 because it has a high moisture barrier property.

  Even if a relatively stressful silicon nitride film is formed as the protective insulating film 51, the cover insulating film 50 made of silicon oxide functions to relieve the stress, so that film peeling due to the protective insulating film 51 is not caused. Is prevented.

  Note that a silicon oxide film or a silicon oxynitride film may be formed as the protective insulating film 51 when barrier properties against moisture are not so required.

  Next, as shown in FIG. 17, a photoresist is applied on the protective insulating film 51, and it is exposed and developed to form an eighth resist pattern 53.

  Then, the cover insulating film 50 and the protective insulating film 51 are dry-etched through the windows 53a and 53b of the eighth resist pattern 53.

  As a result, the first opening 51a is formed in the protective insulating film 51 on the ground electrode film 44b, and the ground electrode 44b is exposed from the first opening 51a. The first opening 51a is also called an ESD (Electro Static Discharge) hole.

  In the pad region II, a second opening 51b is formed through which the bonding pad 35b is exposed.

Then, after removing the eighth resist pattern 53, a dehydration process is performed for 30 minutes under the condition that the substrate temperature is 430 ° C. in an N ₂ atmosphere.

  Next, steps required until a sectional structure shown in FIG.

  First, a coating film made of non-photosensitive polyimide is applied on the protective insulating film 51 to a thickness of about 1200 nm, and then the coating film is baked.

  Next, a resist pattern (not shown) is formed on the coating film, and the first and second windows 55a and 55b are provided by etching the coating film with an etching solution for polyimide while using the resist pattern as a mask. The uppermost passivation film 55 is formed.

  Among these windows, the first window 55a is formed so as to overlap the detection electrode film 44a and the first opening 51a.

  The passivation film 55 functions as a cushioning material that protects the circuit from physical impact.

Further, after removing the resist pattern with a rinsing liquid, the passivation film 55 is cured and cured for 40 minutes under conditions of a substrate temperature of 350 ° C. and an N ₂ flow rate of 18 liters / minute.

  By such curing, the passivation film 55 contracts and the thickness becomes about 1000 nm.

  Here, it is conceivable that the passivation film 55 is made of photosensitive polyimide instead of non-photosensitive polyimide. However, since photosensitive polyimide contains a photosensitive agent and a crosslinking agent, there is a problem that the photosensitive polyimide is softer than non-photosensitive polyimide and is easily damaged when used as a passivation film 55 that can be directly touched by a finger.

  On the other hand, if the passivation film 55 is made of non-photosensitive polyimide as in the present embodiment, the hardness of the passivation film 55 can be made higher than that in the case of using photosensitive polyimide, so that it is necessary to protect the device. The thickness of the passivation film 55 can be made as thin as possible while maintaining a high hardness.

  Subsequently, as shown in FIG. 19, the opening end of the first window 55 a of the passivation film 55 is chamfered. There are the following three methods for chamfering.

First Method In the first method, the opening end of the first window 55a is exposed to a plasma atmosphere consisting only of an inert gas such as argon gas, and chamfering is performed by sputter etching. This sputter etching is performed using an ICP (Inductively Coupled Plasma) type etching apparatus, and the conditions are as follows:
Source power frequency: 13.56 MHz
Source power: about 2000W
Bias power frequency: 400kHz
Bias power power: about 1000W
Reaction pressure: 10 mTorr
Argon flow rate ... 100sccm
Etching time: 12 to 36 seconds In this sputter etching, the opening end of the first window 55a is chamfered by the physical action of argon atomized into plasma.

Second Method In the second method, the opening end of the first window 55a is exposed to a plasma etching atmosphere containing a halogen gas, and the entire surface is etched back by reactive ion etching (RIE). This plasma etching is performed using a parallel plate type plasma etching apparatus, and the conditions are as follows:
RF power frequency: 13.56MHz
RF power: about 1000W
Reaction pressure: about 500 mTorr
Etching time: 13 to 16 seconds Gas flow rate: CHF ₃ : about 100 sccm, argon: about 500 sccm, oxygen: about 10 sccm
According to such plasma etching, chemical etching and physical etching proceed simultaneously by ions or radicals of halogen atoms such as fluorine, and the opening end of the first window 55a is chamfered.

As the etching gas, a mixed gas of CF ₄ , argon, and oxygen may be used instead of these gases. In that case, the flow rate of CF ₄ is set to about 100 sccm, and the flow rates of argon and oxygen are set to about 500 sccm and about 10 sccm, respectively.

Third Method In the third method, the opening end of the first window 55a is chamfered by polishing the passivation film 55 by the CMP method.

  FIG. 20 is an enlarged cross-sectional view of the main part of the CMP apparatus used in the third method.

  In this CMP apparatus, a polishing pad 102 is fixed on a platen 101, and a polishing head 110 is provided above the platen 101.

  The polishing head 110 has a structure in which a retaining ring 103 and a base 111 are connected by a bellows 106. A retaining ring 103 is provided with a chuck 112 for gripping the silicon substrate 10.

The chuck 112 is connected to the retaining ring 103 by a bellows 105 and a flexible inner tube 104. First to third pipes 107 to 109 are passed through the base 101.

  Among these, by increasing the pressure in the first pipe 107, the pressure in the bellows 106 also increases, and the retaining ring 103 is pressed against the platen 101 side.

  Further, when the pressure in the second pipe 108 is increased, the flexible membrane 114 provided on the chuck 112 expands outward, and the silicon substrate 10 is pressed against the polishing pad 102.

  Further, by increasing the pressure in the third pipe 109, the inner tube 104 expands and the chuck 112 is pressed against the polishing pad 102.

  FIG. 21 is a top view of the CMP apparatus.

  As shown in FIG. 21, a slurry feeder 115 is provided above the platen 101. In addition, a conditioner 116 for adjusting the surface state of the polishing pad 102 is provided at a distance from the supply device 115.

  The conditioner 116 has a structure in which the head 116a at the tip thereof rotates, and the head 116a is pressed against the polishing pad 102 simultaneously with the polishing by the polishing head 110 or before the polishing. By such an operation of the conditioner 116, the polishing amount and the in-plane distribution of the polishing amount can be improved.

Using such a CMP apparatus, in this embodiment, the passivation film 55 is polished under the following conditions:
(Polishing conditions)
Type of polishing pad 102: Hard type pad (hardness 60 Shore D or more)
Pressure in inner tube 104 ... 6-8 psi
Retaining ring 103 pressure (pressure in third pipe 108) ... 6.5-9.0 psi
Pressure of the membrane 114 (pressure in the second pipe 108) ... 4.0-6.0 psi
Number of rotations of platen 101 ... 105rpm ± 10%
Number of revolutions of polishing head 110: 70 rpm ± 10%
Slurry supply amount: 120 to 200 ml / min (conditioning conditions)
Conditioning timing: Before polishing (Ex-situ)
Pressure of the head 116a ... 5.0 to 9.0 lbf (weight pound)
Number of rotations of the head 116a ... 95 rpm ± 10%
Number of rotations of platen 101 ... 105rpm ± 10%
Although it is conceivable to polish the passivation film 55 under polishing conditions other than those described above, the film thickness of the passivation film 55 after polishing varies greatly within the substrate surface, so that the film thickness distribution variation within the substrate surface varies. In order to minimize it, it is preferable to adopt this polishing condition.

  Further, when chamfering is performed by the CMP method in this way, heat treatment may be performed on the passivation film 55 after CMP to remove moisture absorbed by the passivation film 55 during CMP. The heat treatment is performed, for example, in the atmosphere at a substrate temperature of 300 ° C. for about 10 minutes.

  In the present embodiment, the passivation film 55 is shaved by 10 to 30% of the original thickness by using any of the first to third methods described above, and the opening end of the first window 55a is chamfered. When the original thickness of the passivation film 55 is 1000 nm, the amount of shaving is about 100 to 300 nm.

  Instead of the first to third methods described above, it is also conceivable to chamfer the open end of the first window 55a using a plasma ashing device. The plasma ashing apparatus is usually used to oxidize and remove organic substances such as a resist pattern with a mixed gas of oxygen and nitrogen.

  However, when such a plasma ashing apparatus is used in this embodiment, the surface of the passivation film 55 becomes excessively high. As a result, the polyimide bond constituting the passivation film 55 is easily broken, the strength of the passivation film 55 is reduced, and the passivation film 55 does not function as a buffer material.

  On the other hand, in the first to third methods described above, the opening end of the first window 55a can be chamfered while preventing the strength of the polyimide from decreasing.

  Thus, the basic structure of the surface shape sensor according to the present embodiment is completed.

  In this surface shape sensor, a capacitor C is formed between the finger F and the detection electrode film 44a by tracing (sweeping) the passivation film 55 with the finger (subject) F as shown in FIG. Since the capacitance of the capacitor C changes due to the unevenness (fingerprint) on the surface of the finger F, a fingerprint image can be obtained by reading the difference in capacitance with the detection electrode film 44a.

  Further, since the first window 55a is greatly opened so that the first window 55a overlaps both the first opening 51a and the detection electrode film 44a, the finger F can be surely swept by sweeping the passivation film 55 with the finger F. The ground electrode film 44b is touched. Therefore, the static electricity charged on the finger F is surely released from the ground electrode 44b to the silicon substrate 10, so that the circuit formed on the silicon substrate 10 can be prevented from being destroyed by the static electricity.

  FIG. 23 is a plan view of the sensor region I of this surface shape sensor.

  As shown in FIG. 23, a plurality of detection electrode films 44a are formed in a matrix, and four detection electrode films 44a centering on the ground electrode film 44b function as one pixel. Although the planar size of each electrode film 44a, 44b is not particularly limited, in this embodiment, L1 is about 50 μm and L2 is about 6 μm as shown in the figure.

  According to the present embodiment described above, the chamfering of the opening end of the first window 55a formed in the passivation film 55 is performed in the step shown in FIG. And the friction with the passivation film 55 is reduced.

  Therefore, even if the passivation film 55 is traced with the finger F as shown in FIG. 22, a large force is not applied from the finger F to the first window 55a, so that the film is peeled off on the passivation film 55 near the first window 55a. Can be prevented. As a result, even if the surface shape sensor is used for a long period of time, the passivation film 55 is hardly deteriorated, and the reliability of the surface shape sensor can be improved.

  Furthermore, by chamfering in this way, foreign matter P such as finger oil or the like is less likely to accumulate inside the first window 55a. Therefore, the capacitance of the capacitor C between the finger F and the detection electrode film 44a is suppressed from fluctuating due to the foreign matter P, and the unevenness of the fingerprint can be accurately read based on the capacitance. The problem that the detection rate is lowered can be solved.

  Further, when the first window 55a is chamfered, the opening end of the first opening (ESD hole) 51a formed in the protective insulating film 51 is also chamfered, so that the finger can be prevented from being caught in the first opening 51a. It is also possible to suppress peeling of the insulating film 51.

Comparative Example FIG. 24 is a cross-sectional view of a surface shape sensor according to a comparative example.

  As shown in FIG. 24, in this comparative example, the passivation film 55 is not chamfered, and the side surfaces of the first window 55a and the first opening 51a stand in a direction perpendicular to the in-plane direction. Yes.

  When the passivation film 55 is traced with the finger F in this state, the finger F is caught in the first window 55a and the first opening 51a, and the passivation film 55 and the protective insulating film 51 are peeled off at the portions indicated by the arrows A and B. In addition, the reliability of the surface shape sensor decreases.

  Furthermore, since the side surfaces of the first window 55a and the first opening 51a are vertical, the foreign matter P such as the oil and fat of the finger F is likely to accumulate inside the first window 55a and the first opening 51a. May fall.

  On the other hand, in the present embodiment, the side surfaces of the first window 55a and the first opening 51a are inclined with respect to the in-plane direction due to the chamfering as described above, so that the films 51 and 55 can be prevented from peeling off. At the same time, the foreign matter P is less likely to accumulate inside the first window 55a and the first opening 51a.

(2) Second Embodiment FIGS. 25 and 26 are cross-sectional views in the middle of manufacturing a surface shape sensor according to the present embodiment. In these drawings, the elements described in the first embodiment are denoted by the same reference numerals as those in the first embodiment, and the description thereof is omitted below.

  In order to manufacture this surface shape sensor, first, the process of FIGS. 1-17 demonstrated in 1st Embodiment is performed.

  Then, after removing the eighth resist pattern 53 (see FIG. 17), the opening end of the first opening 51a of the protective insulating film 51 made of silicon nitride is chamfered as shown in FIG.

  This chamfering is performed in the same manner as in the process of FIG. 19 of the first embodiment. (I) Sputter etching in a plasma atmosphere consisting only of an inert gas such as argon gas; This is performed by scraping the surface of the protective insulating film 51 by any one of ion etching and (iii) CMP.

  Among these, the conditions of the first method (i) and the second method (ii) are the same as those described with reference to FIG.

  On the other hand, in the CMP method in the third method (iii), the following conditions are adopted using the CMP apparatus described in FIGS.

(Polishing conditions)
Type of polishing pad 102: Laminated type pad (lower layer is urethane layer)
Pressure in inner tube 104: 3.5 to 5.5 psi
Retaining ring 103 pressure (pressure in third pipe 108) ... 4.5-6.5 psi
Pressure of the membrane 114 (pressure in the second pipe 108) ... 2.0 to 4.0 psi
Number of rotations of platen 101 ... 105rpm ± 10%
Number of revolutions of polishing head 110: 70 rpm ± 10%
Slurry supply rate: 250-250 ml / min (conditioning conditions)
Conditioning timing: Simultaneous with polishing (In-situ)
Pressure of head 116a ... 6.0 to 9.0 lbf (pound weight)
Number of rotations of the head 116a ... 95rpm ± 10%
Number of rotations of platen 101 ... 105rpm ± 10%
In any of the first to third methods (i) to (iii), the amount of the protective insulating film 51 is reduced to 10 to 20% of the original thickness. For example, when the original thickness of the protective insulating film 51 is 1000 nm, the shaving amount is 100 to 200 nm.

  Thereafter, the same process as that of FIG. 18 of the first embodiment is performed to form a passivation film 55 made of non-photosensitive polyimide on the protective insulating film 51. Then, as shown in FIG. The opening end of the window 55a is chamfered. Since this chamfering method has been described with reference to FIG. 19 in the first embodiment, it is omitted here.

  Thus, the basic structure of the surface shape sensor according to this embodiment is completed.

  In the present embodiment described above, as shown in FIG. 25, the opening end of the first opening 51 a of the protective insulating film 51 is chamfered in advance before forming the passivation film 55. As a result, in the step of chamfering the passivation film 55 (see FIG. 26), the opening end of the first opening 51a is shaved and becomes smoother than in the first embodiment. Becomes difficult to be caught, and the protective insulating film 51 can be reliably prevented from peeling off.

  As mentioned above, although embodiment of this invention was described in detail, this invention is not limited to said each embodiment. For example, the sweep type surface shape sensor has been described above, but the present invention can also be applied to an area type (surface type) surface shape sensor.

  The features of the present invention are added below.

(Appendix 1) a semiconductor substrate;
An interlayer insulating film formed above the semiconductor substrate;
A detection electrode film and a ground electrode film formed on the interlayer insulating film at a distance from each other;
A protective insulating film formed on each of the interlayer insulating film, the detection electrode film, and the ground electrode film, and having an opening through which the ground electrode film is exposed;
A passivation film that is formed on the protective insulating film and has a window that overlaps the detection electrode film and the opening;
A surface shape sensor, wherein an opening end of the window is chamfered.

  (Additional remark 2) The surface shape sensor of Additional remark 1 characterized by the chamfering of the opening end of the said opening.

(Appendix 3) A step of forming an interlayer insulating film above the semiconductor substrate;
Forming a detection electrode film and a ground electrode film on the interlayer insulating film at a distance from each other;
Forming a protective insulating film on each of the interlayer insulating film, the detection electrode film, and the ground electrode film;
Forming an opening in the protective insulating film through which the ground electrode film is exposed;
Forming a passivation film having a window overlapping the detection electrode film and the opening on the protective insulating film;
Chamfering the open end of the window;
A method of manufacturing a surface shape sensor, comprising:

  (Additional remark 4) The process of chamfering the opening end of the said window is performed by exposing this open end in etching atmosphere, The manufacturing method of the surface shape sensor of Additional remark 3 characterized by the above-mentioned.

  (Additional remark 5) The said etching atmosphere is the atmosphere of the sputter etching which consists only of inert gas, or the atmosphere of the plasma etching containing halogen gas, The manufacturing method of the surface shape sensor of Additional remark 4 characterized by the above-mentioned.

  (Additional remark 6) The process of chamfering the opening edge of the said window is performed by grind | polishing the said passivation film by a chemical mechanical polishing method, The manufacturing method of the surface shape sensor of Additional remark 3 characterized by the above-mentioned.

  (Appendix 7) The chemical mechanical polishing method uses a hard type pad having a hardness of 60 Shore D or more, a pressure in the inner tube of 6 to 8 psi, a pressure of the retaining ring of 6.5 to 9.0 psi, The membrane pressure is 4.0 to 6.0 psi, the platen rotation speed is 105 rpm ± 10%, the polishing head rotation speed is 70 rpm ± 10%, and the slurry supply rate is 120 to 200 ml / min. The manufacturing method of the surface shape sensor of Claim 6.

  (Additional remark 8) Conditioning for adjusting the surface state of the polishing pad used by the said chemical mechanical polishing method is performed before the said grinding | polishing, The manufacturing method of the surface shape sensor of Additional remark 6 characterized by the above-mentioned.

  (Supplementary Note 9) The conditioning is performed at a conditioning head pressure of 5.0 to 9.0 lbf, a rotational speed of the head of 95 rpm ± 10%, and a rotational speed of the platen of 105 rpm ± 10%. The surface shape sensor according to appendix 8.

  (Supplementary note 10) The method for manufacturing a surface shape sensor according to supplementary note 6, further comprising a step of performing a heat treatment on the passivation film and dehydrating the passivation film after polishing the passivation film.

  (Additional remark 11) Before forming the said passivation film, it further has the process of chamfering the opening end of the said opening, The manufacturing method of the surface shape sensor of Additional remark 3 characterized by the above-mentioned.

  (Additional remark 12) The process of chamfering the opening end of the said opening is performed by exposing the opening end of this opening in etching atmosphere, The manufacturing method of the surface shape sensor of Additional remark 11 characterized by the above-mentioned.

  (Supplementary note 13) The method for manufacturing a surface shape sensor according to supplementary note 11, wherein the step of chamfering the opening end of the opening is performed by polishing the protective insulating film by a chemical mechanical polishing method.

  (Supplementary Note 14) The chemical mechanical polishing method uses a laminated type pad, the pressure in the inner tube is 3.5 to 5.5 psi, the pressure of the retaining ring is 4.5 to 6.5 psi, and the pressure of the membrane is 2 Appendix 13 is characterized in that it is carried out at 0.0 to 4.0 psi, the platen rotation speed is 105 rpm ± 10%, the polishing head rotation speed is 70 rpm ± 10%, and the slurry supply rate is 250 to 250 ml / min. The surface shape sensor described.

  (Additional remark 15) Conditioning for adjusting the surface state of the polishing pad used with the said chemical mechanical polishing method is performed simultaneously with the said grinding | polishing, The manufacturing method of the surface shape sensor of Additional remark 13 characterized by the above-mentioned.

  (Supplementary Note 16) The conditioning is performed at a conditioning head pressure of 6.0 to 9.0 lbf, a head rotation speed of 95 rpm ± 10%, and a platen rotation speed of 105 rpm ± 10%. The manufacturing method of the surface shape sensor of Supplementary Note 15.

FIGS. 1A and 1B are cross-sectional views (part 1) in the middle of manufacturing the surface shape sensor according to the first embodiment of the present invention. 2A and 2B are cross-sectional views (part 2) in the middle of manufacturing the surface shape sensor according to the first embodiment of the present invention. FIGS. 3A and 3B are cross-sectional views (part 3) in the middle of manufacturing the surface shape sensor according to the first embodiment of the present invention. FIG. 4 is a sectional view (No. 4) in the middle of manufacturing the surface shape sensor according to the first embodiment of the present invention. FIG. 5: is sectional drawing (the 5) in the middle of manufacture of the surface shape sensor which concerns on 1st Embodiment of this invention. FIG. 6 is a sectional view (No. 6) in the middle of manufacturing the surface shape sensor according to the first embodiment of the present invention. FIG. 7 is a sectional view (No. 7) in the middle of manufacturing the surface shape sensor according to the first embodiment of the present invention. FIG. 8 is a sectional view (No. 8) in the middle of manufacturing the surface shape sensor according to the first embodiment of the present invention. FIG. 9 is a sectional view (No. 9) in the middle of manufacturing the surface shape sensor according to the first embodiment of the present invention. FIG. 10: is sectional drawing (the 10) in the middle of manufacture of the surface shape sensor which concerns on 1st Embodiment of this invention. FIG. 11: is sectional drawing (the 11) in the middle of manufacture of the surface shape sensor which concerns on 1st Embodiment of this invention. FIG. 12 is a sectional view (No. 12) in the middle of manufacturing the surface shape sensor according to the first embodiment of the present invention. FIG. 13: is sectional drawing (the 13) in the middle of manufacture of the surface shape sensor which concerns on 1st Embodiment of this invention. FIG. 14 is a cross-sectional view (No. 14) in the middle of manufacturing the surface shape sensor according to the first embodiment of the present invention. FIG. 15: is sectional drawing (the 15) in the middle of manufacture of the surface shape sensor which concerns on 1st Embodiment of this invention. FIG. 16: is sectional drawing (the 16) in the middle of manufacture of the surface shape sensor which concerns on 1st Embodiment of this invention. FIG. 17 is a sectional view (No. 17) in the middle of manufacturing the surface shape sensor according to the first embodiment of the present invention. FIG. 18 is a sectional view (No. 18) in the middle of manufacturing the surface shape sensor according to the first embodiment of the present invention. FIG. 19 is a sectional view (No. 19) in the middle of manufacturing the surface shape sensor according to the first embodiment of the present invention. FIG. 20 is an enlarged cross-sectional view of a main part of the CMP apparatus used in the first embodiment of the present invention. FIG. 21 is a top view of the CMP apparatus used in the first embodiment of the present invention. FIG. 22 is a cross-sectional view for explaining the operation of the surface shape sensor according to the first embodiment of the present invention. FIG. 23 is a plan view of the surface shape sensor according to the first embodiment of the present invention. FIG. 24 is a cross-sectional view of a surface shape sensor according to a comparative example. FIG. 25: is sectional drawing (the 1) in the middle of manufacture of the surface shape sensor which concerns on 2nd Embodiment of this invention. FIG. 26: is sectional drawing (the 2) in the middle of manufacture of the surface shape sensor which concerns on 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Silicon substrate, 11 ... Element isolation insulating film, 12 ... 1st p well, 13 ... 2nd p well, 14 ... Gate insulating film, 15 ... Gate electrode, 16 ... Wiring, 17a-17c ... 1st-3rd source / Drain extension, 18 ... insulating spacers, 19 a to 19 c ... first to third source / drain regions, 20 ... high melting point silicide layer, 21 ... cover insulating film, 22 ... first insulating film, 23 ... first interlayer insulating film , 23a to 23e ... first to fifth contact holes, 24 ... first resist pattern, 24a to 24e ... windows, 25a to 25e ... first to fifth conductive plugs, 26 ... first metal laminated film, 26a ... one layer Metal wiring, 27 ... second resist pattern, 28 ... second insulating film, 29 ... first cap insulating film, 30 ... second interlayer insulating film, 30a ... first hole, 32 ... third resist pattern, 4 ... 6th conductive plug, 35 ... 2nd metal laminated film, 36 ... 4th resist pattern, 37 ... Cover insulating film, 38 ... 3rd insulating film, 39 ... Sacrificial insulating film, 40 ... 3rd interlayer insulating film, 43 ... 5th resist pattern, 43a, 43b ... Window, 44 ... Conductive film, 44a ... Detection electrode film, 44b ... Ground electrode film, 46 ... 6th resist pattern, 48 ... 7th resist pattern, 48a ... Window, 50 ... Cover insulating film, 51... Protective insulating film, 53... Eighth resist pattern, 53 a, 53 b .. window, 55 .. passivation film, 55 a, 55 b.

Claims (5)

A semiconductor substrate;
An interlayer insulating film formed above the semiconductor substrate;
A detection electrode film and a ground electrode film formed on the interlayer insulating film at a distance from each other;
A protective insulating film formed on each of the interlayer insulating film, the detection electrode film, and the ground electrode film, and having an opening through which the ground electrode film is exposed;
A passivation film that is formed on the protective insulating film and has a window that overlaps the detection electrode film and the opening;
A surface shape sensor, wherein an opening end of the window is chamfered.   The surface shape sensor according to claim 1, wherein an opening end of the opening is chamfered. Forming an interlayer insulating film above the semiconductor substrate;
Forming a detection electrode film and a ground electrode film on the interlayer insulating film at a distance from each other;
Forming a protective insulating film on each of the interlayer insulating film, the detection electrode film, and the ground electrode film;
Forming an opening in the protective insulating film through which the ground electrode film is exposed;
Forming a passivation film having a window overlapping the detection electrode film and the opening on the protective insulating film;
Chamfering the open end of the window;
A method of manufacturing a surface shape sensor, comprising:   4. The method of manufacturing a surface shape sensor according to claim 3, wherein the step of chamfering the opening end of the window is performed by polishing the passivation film by a chemical mechanical polishing method.   The method of manufacturing a surface shape sensor according to claim 3, further comprising a step of chamfering the opening end of the opening before forming the passivation film.

Images