The manufacture method of multifunction integrated sensor chip
Technical field
The invention belongs to micromechanics electronic system (MEMS) technology and integrated circuit micro-processing technology field, be specifically related to the method for the multifunction integrated sensor chip of a kind of application micromechanics electronic system (MEMS) technology and integrated circuit micro-processing technology making.
Background technology
Current, the transducer manufacturing technology of various simple functions based on the MEMS technology is more and more ripe, and the sensor technology forward is integrated, the intelligent direction development.Transducer integrated has three kinds of approach: the one, and a plurality of functions are identical, or the close set of sensors of function becomes one dimension or two-dimentional sensor array; Second kind is that transducer and integrated circuit are integrated in on the chip piece; The third be meant sensors of various types is carried out integrated, as the transducer of sensing units such as integrated pressure, temperature, humidity, flow, acceleration.
At present, domestic to the integrated research emphasis of transducer at above-mentioned second kind, by unified CMOS technology, or utilize upside-down mounting (flip-chip) technology, and transducer and treatment circuit are integrated on the chip piece, improve the accuracy of detection of transducer, realize intellectuality, expand its range of application.And fewer to the research of integrated various difference in functionality transducers on a tube core, mainly be integrated temperature, two kinds of devices of humidity.
Many abroad to the third integrated approach research, studied microenvironment work station (Mini-weather stations) as NASA-JPL (American National aviation and NASA-jet propulsion laboratory), integrated pressure, temperature, little humidity, radiation sensor and densimeter and laser-Doppler windage scale etc.; The ST-3000 type intelligence sensor chip size of U.S. Honywell company is 3 * 4 * 2mm
3, integrated CPU, EPROM and static pressure, pressure reduction, three kinds of transducers of temperature; U.S. EG﹠amp; The compound mechanics transducer of G IC Sensors company development, any three-dimensional vibrating acceleration, speed, displacement of Measuring Object simultaneously; Nippon Electric Company, Ltd. has been developed into the integrated FET transducer that detects glucose, urea, vitamin K and four kinds of compositions of albumin.
The advantage of multifunction integrated sensor mainly is: thus sensor is spreaded over a whole area from one point even multidimensional to body realization information, become one-parameter and detect and be the multi-parameter detection.The integrated sensor technology that will make obtains income in the following areas: (1) volume is little, light weight, cost are low; (2) zmodem, confidence level height, stable performance; (3) increase the measurement dimension, improve spatial resolution, expanded the coverage rate of room and time; (4) promote detection performance, increase the validity of response, improve the reliability and maintainability of system.The integrated performance requirement that also will reduce to single-sensor, but when a plurality of sensing elements are integrated, take into full account the problems such as performance complement, Electro Magnetic Compatibility and resource-sharing of sensing element.
But multiple sensors is integrated in the following difficulty of existence on the chip: the one, may be incompatible between the processing technology of various variety classes transducers; The second, if certain transducer on the same tube core need directly contact with external environment, and other transducer must seal, and will cause the difficulty of integrated encapsulation.Even so, if by the integrated sensor type of careful selection, rationally arrange encapsulating structure and processing technology, the problems referred to above can be resolved fully.
Raising along with the human living standard, and to living environment require more and more higher, need the environmental quality in life activity place be detected,, and require portable, easy to use as pressure, temperature, humidity etc. and the closely-related index of human comfort.
Summary of the invention
The object of the present invention is to provide a kind of manufacture method of multifunction integrated sensor chip, utilize MEMS (micro electro mechanical system) (MEMS) technology and integrated circuit micro-processing technology, on singulated dies, make the multifunction integrated sensor be used to detect about human comfort index of correlation such as pressure, temperature and humidity.
Realize that the technical solution that above-mentioned purpose is taked is, a kind of manufacture method of multifunction integrated sensor chip, it is characterized in that, adopt micromechanics electronic system technology and integrated circuit micro-processing technology on the tube core of a 5mm * 5mm area, to produce and to distinguish responsive pressure, temperature, three sensor units of humidity; Its manufacture method comprises the following steps:
1) will form the silicon dioxide layer of 800 ± 50nm through the n type monocrystalline silicon piece that cleans through peroxidating;
2) apply photoresist then on silicon dioxide layer, add the resistor stripe mask plate, front lighting carves the resistor stripe planform of pressure unit and temperature sensor unit, and diffusion concentration is 2 * 10
19/ cm
3The boron ion, forming junction depth is the p type resistor stripe of 2~2.5 μ m;
3) forming thickness by low pressure gas phase deposition again on silicon dioxide layer is that 120nm ± 20nm silicon nitride is as the stress matching layer;
4) add back of the body chamber mask plate, part silicon dioxide is removed in back side photoetching, adopts the mixture corrosive liquid (EPW) of ethylenediamine, catechol and water that n type silicon base is carried out anisotropic etch, and forming thickness is the C type cup pressure chamber of 25 μ m;
5) add resistance hole mask plate, positive photoetching forms the resistance hole;
6) to carry out the sputter ratio be Si: Al=1 in the front then: 99 silica-alumina material, thickness are 2.5 μ m~3.0 μ m;
7) add the electrode mask plate, the etching electrode shape forms the contact conductor of pressure, temperature, humidity sensor unit, and forms the interdigital electrode of humidity sensor unit;
8) in temperature be 480 ℃ N
2Carry out 30 minutes metalized in the environment, form ohmic contact;
9) carry out the vacuum static electricity bonding, n type monocrystalline silicon piece is encapsulated on the thick Pyrex of 2mm, and to form vacuum degree in cavity area be 10
-5The vacuum chamber of millitorr is used for testing environment pressure;
10) evenly apply humidity-sensitive film in the humidity unit;
11) be diced into singulated dies at last.
The chip volume that method of the present invention is made is little, energy consumption is low, is encapsulated in easily as on the popular portable instrument equipment such as wrist-watch, mobile phone, the convenient use.
Description of drawings
Fig. 1 is a structure principle chart of the present invention.
Fig. 2 is the resistor stripe structural representation of pressure unit among the present invention.
Fig. 3 is the fundamental diagram of pressure unit of the present invention.
Fig. 4 is the resistor stripe structural representation of temperature unit among the present invention.
Fig. 5 is the electrode structure schematic diagram of humidity unit among the present invention.
Fig. 6 is a photo in kind of the present invention.
Below in conjunction with accompanying drawing structural principle of the present invention and operation principle are elaborated.
Embodiment
With reference to Fig. 1, the present invention makes three sensing units by MEMS technology and integrated circuit micro-processing technology on (100) crystal face, 5mm * 5mm tube core: pressure I, temperature II and humidity unit III, the back side of pressure unit I is C type silicon cup, temperature II and humidity unit III are arranged in solid zone of tube core, to eliminate the influence of pressure to the temperature and humidity unit, this chip is encapsulated on the Pyrex 1 by vacuum bonding technology, and key technology wherein is the processing compatibility in the manufacturing process.Three unit based on the effect difference, wherein pressure unit is based on piezoresistive effect, the pressure that is mainly used in testing environment changes; Temperature unit is used for the testing environment variation of temperature based on thermal resistance effect; The humidity unit is used for the variation of testing environment humidity based on capacitance principle.
Basic manufacture craft is as follows: n type (001) monocrystalline silicon piece 2 that process is cleaned forms the silicon dioxide layer 4 of 800 ± 50nm through peroxidating; Apply photoresist, add the resistor stripe mask plate, front lighting carves the resistor stripe shape of pressure unit I and temperature unit II, and diffusion concentration is 2 * 10
19/ cm
3The boron ion, forming junction depth is the p type resistor stripe layer 3 of 2~2.5 μ m, comprising four the resistor stripe lines 7 of pressure unit I and the resistor stripe 10 of temperature unit II; Forming thickness by low pressure gas phase deposition (LPCVD) is that 120nm ± 20nm silicon nitride layer 5 is as the stress matching layer; Add back of the body chamber mask plate, part silicon dioxide layer 4 is removed in back side photoetching, adopts EPW (ethylenediamine, the mixture of catechol and water) corrosive liquid that n type monocrystal silicon substrate 2 is carried out anisotropic etch, and forming thickness is the C type cup pressure chamber of 25 μ m; Add resistance hole mask plate, positive photoetching forms the resistance hole; To carry out the sputter ratio be Si: Al=1 in the front then: 99 silica-alumina material, thickness are 2.5~3.0 μ m; Add the electrode mask plate, etch contact conductor 8 and press welding block series 9, the contact conductor 11 of temperature unit II and contact conductor 14 and the press welding block series 15 of press welding block series 12 and humidity unit III of pressure unit I, and form the interdigital electrode 13 of humidity unit III; In temperature 480 ℃ N
2Carry out 30 minutes metalized in the environment, help forming ohmic contact; Carry out the vacuum static electricity bonding, silicon is encapsulated on the thick Pyrex of 2mm 1, and to form vacuum degree in cavity area be 10
-5The vacuum chamber of millitorr is used for testing environment pressure; Evenly apply humidity-sensitive film 6 in the humidity unit; Be diced into singulated dies at last.
Operation principle to three sensing units is introduced below.
Pressure list I mainly comprises four p type pressure drag resistor stripes 7, contact conductor 8 and press welding block series 9, and the effect of press welding block series 9 is exactly to realize in the chip and the outer lead-in wire of chip by gold ball bonding.Four resistor stripes 7 are all along silicon fiml
The crystal orientation is arranged in stress raiser, and contour structures is seen schematic diagram 2.The back side of pressure unit I forms cavity by anisotropic corrosion technique, forms vacuum behind tube core and Pyrex 1 vacuum bonding.When ambient pressure environment P acts on the silicon fiml, silicon fiml deforms, degree of the disturbing W of generation
P, as shown in Figure 3.Based on piezoresistive effect, wherein the resistance of two resistor stripes becomes big, and the resistance of two resistor stripes diminishes in addition, and the Hui Sideng full-bridge of being made up of four resistor stripes is under stabilized power source encourages, the signal of telecommunication that output is directly proportional with ambient pressure environment P is realized the detection of pressure to external world.
Temperature unit II comprises by diffusion technology and forms structure p type resistor stripe 10 and sputter, the etching technics contact conductor 11 and the press welding block series 12 that form as shown in Figure 4.P type resistor stripe 10 is arranged in [100] crystal orientation of silicon chip, because the piezoresistance coefficient in [100] crystal orientation is less, can reduce the influence of pressure to temperature unit.The resistivity of resistor stripe as shown in the formula:
In the formula, μ
nAnd μ
pBe respectively n type and p type mobility of charge carrier rate, q is an electron charge, N and P mix respectively n type and p type carrier concentration among the Si.
For p type silicon, have p>>N, so
Wherein, μ
pWith the temperature T relation of being inversely proportional to, so along with variation of temperature, the proportional variation of electricalresistivity, according to following formula,
In the formula, R is the resistance of resistor stripe, and ρ is a resistivity, and L is the length of resistor stripe, and S is the cross-sectional area of resistor stripe.
By press welding block series 12, draw outer lead through gold ball bonding, just can obtain the proportionate relationship of ambient temperature T and resistor stripe resistance R, thereby record T.
Humidity unit III forms the aluminium lamination that thickness is 2.5~3.0 μ m by sputtering technology on silicon, form interdigitation electrode 13, contact conductor 14 and press welding block series 15 by etching technics again, as shown in Figure 5, wherein interdigitation electrode 13 comprises electrode 51 pole plates and electrode 52 pole plates.Select for use the stronger wet sensory material of moisture absorption and dehumidification ability evenly to be coated in the space of interdigital electrode, forming thickness is the humidity-sensitive film 6 of 3 μ m.When the humidity of environment changes, the proportional variation of the DIELECTRIC CONSTANT of humidity-sensitive film 6,
According to
, wherein S, d are sectional area and two electrode spacings that are respectively electrode, and S, d are constant, therefore by press welding block series 15, draw outer lead through gold ball bonding, just can record and the proportional capacitor C value of the variation of ambient humidity.
Shown in Figure 6 is the multifunction integrated sensor chip that adopts method preparation of the present invention, have that volume is little, integrated level is high, multi-functional, low cost and other advantages, can be widely used in the parameters relevant such as testing environment pressure, temperature, humidity with human comfort, offer the subenvironment that environment conditioning equipment realizes that comfort level is satisfied, and can encapsulate with portable apparatus, as wrist-watch, mobile phone etc., easy to use.