CN105712286B - The preparation method of MEMS - Google Patents
The preparation method of MEMS Download PDFInfo
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- CN105712286B CN105712286B CN201410720429.8A CN201410720429A CN105712286B CN 105712286 B CN105712286 B CN 105712286B CN 201410720429 A CN201410720429 A CN 201410720429A CN 105712286 B CN105712286 B CN 105712286B
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Abstract
A kind of preparation method of MEMS,In the front deposition the first film of Semiconductor substrate,Above-mentioned deposition uses high temperature,Because the thermal coefficient of expansion of the first film is more than the thermal coefficient of expansion of the Semiconductor substrate,After thus cooling down,Semiconductor substrate and the first film occur both ends to the problem of the tilting of Semiconductor substrate front,To solve the above problems,Continue to form the second film at the Semiconductor substrate back side,And the thermal coefficient of expansion that laser heat treatment makes its thermal coefficient of expansion be more than Semiconductor substrate is carried out to second film,During laser heat treatment,The second film both ends at Semiconductor substrate and its back side tend to tilt to the Semiconductor substrate back side,The tilting of above-mentioned tilting trend and the first film is offset,After thus cooling down,Flat Semiconductor substrate can be obtained,The first film and the second film,And flat the first film after release still in flat state,So as to make to obtain the high MEMS of movable member sensing sensitivity in a manner of low cost.
Description
Technical field
The present invention relates to technical field of manufacturing semiconductors, more particularly to a kind of preparation method of MEMS.
Background technology
Since later 1980s, with MEMS (Micro Electro Mechanical
System, MEMS) technology development, some semiconductor devices, such as various sensors realize microminaturization, realize batch
Production, turn into the Main way of future development.
In MEMS, the general movable member with fixed component and suspension in the cavities, MEMS institute is utilized
Place's environment changes, such as after motion, causes some electrical parameters between movable member and fixed component, such as electric capacity to occur
Change so as to be sensed.Above-mentioned movable member is generally thin film.
Practical study shows that above-mentioned MEMS is in manufacturing process, because movable member film is high temperature deposition, thus
After device cooling, often there is warpage, uneven phenomenon, this will influence the biography of MEMS due to stress release reason in the film
Sense.
In view of the above-mentioned problems, prior art also has some solutions.Such as：The material of low stress is developed as movable part
Part, but this will cause the technique for being related to movable member to change therewith, cause process window smaller, cost increase, the opposing party
Face, it is relatively low for some low-stress materials, its sensing sensitivity.In another example：Using tensile stress and compression stress, both should
Alternately for superposition deposition to form movable film, this will also result in process costs increase and movable member to the opposite material of power type
Sensitivity step-down.
In view of this, the present invention provides a kind of preparation method of new MEMS, and cost is low and does not influence movable member
Sensing sensitivity.
The content of the invention
The present invention solves the problems, such as be how to provide a kind of preparation method of MEMS, cost is low and does not influence movable part
The sensing sensitivity of part.
To solve the above problems, the present invention provides a kind of preparation method of MEMS, including：
Semiconductor substrate is provided, in Semiconductor substrate front deposition the first film, the thermal expansion of the first film
Coefficient is more than the thermal coefficient of expansion of the Semiconductor substrate；
Continue to form the second film at the Semiconductor substrate back side, carrying out laser heat treatment to second film makes its heat swollen
Swollen coefficient is more than the thermal coefficient of expansion of the Semiconductor substrate；
After cooling, release is carried out to the first film and forms it into movable member.
Alternatively, the material of the Semiconductor substrate is silicon, and the material of the first film is SiGe, copper or aluminium.
Alternatively, the first film is formed using furnace process, and temperature range is 300 DEG C~500 DEG C.
Alternatively, carrying out laser heat treatment to second film makes its thermal coefficient of expansion be more than the Semiconductor substrate
Thermal coefficient of expansion makes the change of its density realize greatly by carrying out laser heat treatment to second film.
Alternatively, second film can absorb ultraviolet, and second film absorbs ultraviolet in laser heat treatment
Density becomes big afterwards.
Alternatively, the material of second film is SiGe or unformed silicon.
Alternatively, the laser heat treatment that second film is carried out is heat-treated for Ultra-Violet Laser.
Alternatively, the temperature of the Ultra-Violet Laser heat treatment is more than 1000 DEG C.
Alternatively, the wave-length coverage of the Ultra-Violet Laser heat treatment is：100nm~400nm.
Alternatively, the energy of the Ultra-Violet Laser heat treatment is less than 2J/cm2。
Alternatively, the time of the Ultra-Violet Laser heat treatment is less than 1 μ s.
Alternatively, the movable sensitive film that the movable member is single armed beam or both ends support.
Alternatively, the Semiconductor substrate is silicon substrate or SOI, and movable member is formed it into the first film release
It is to be realized by the silicon substrate or SOI of erosion removal subregion.
Alternatively, there is sacrifice layer in the Semiconductor substrate, movable member is formed it into the first film release
It is to be realized by removing the sacrifice layer.
Compared with prior art, technical scheme has advantages below：1) in Semiconductor substrate front deposition the
One film, above-mentioned deposition process use high temperature, because the thermal coefficient of expansion of the first film is more than the thermal expansion of the Semiconductor substrate
Coefficient, thus the phenomenon tilted to Semiconductor substrate front occurs in the both ends of Semiconductor substrate and the first film, to solve
Above mentioned problem, continue to form the second film at the Semiconductor substrate back side, carrying out laser heat treatment to the second film makes its thermal expansion
Coefficient is more than the thermal coefficient of expansion of Semiconductor substrate, because the thermal coefficient of expansion of the second film after processing is more than Semiconductor substrate
Thermal coefficient of expansion and above-mentioned processing be high temperature, thus, during laser heat treatment, second film two at Semiconductor substrate and its back side
End tends to tilt to the Semiconductor substrate back side, and the tilting of above-mentioned tilting trend and the first film is offset, thus after cooling, can be obtained
Flat Semiconductor substrate, the first film and the second film, and flat the first film after release still in flat state, so as to
Make to obtain the high MEMS of movable member sensing sensitivity in a manner of low cost.
2) in alternative, the second film can absorb ultraviolet, and second film absorbs ultraviolet in laser heat treatment
Density becomes big after line, and the thermal coefficient of expansion that density becomes the second big film becomes big, is high temperature when being heat-treated in addition, subsequently only needs to drop
Temperature can obtain non-warpage, flat the first film, density and become the second film greatly and Semiconductor substrate.
3) in alternative, the first film for having two kinds of releases flat forms the mode of MEMS movable member：A) partly lead
Body substrate is silicon substrate or SOI, and the silicon substrate or SOI of erosion removal subregion are to form the cavity of suspension the first film；b)
There is sacrifice layer in Semiconductor substrate, remove the sacrifice layer to form the cavity of suspension the first film.
Brief description of the drawings
Fig. 1 to Fig. 7 is structural representation of the MEMS in one embodiment of the invention in the different production phases.
Embodiment
As described in the background art, existing MEMS after making, due to stress released by movable member therein
Reason is put, warpage often occurs, uneven phenomenon, this will influence the sensing of MEMS.In view of the above-mentioned problems, the present invention proposes：
High temperature is used in Semiconductor substrate front deposition the first film, above-mentioned deposition process, due to the thermal coefficient of expansion of the first film
More than the thermal coefficient of expansion of the Semiconductor substrate, thus Semiconductor substrate and the first film occur both ends to Semiconductor substrate
The phenomenon that front tilts, the first film of such warpage will also result in movable member injustice after release forms movable member, be
Solve the above problems, the present invention is proposed to continue to form the second film at the Semiconductor substrate back side, and laser heat is carried out to the second film
Processing makes its thermal coefficient of expansion more than the thermal coefficient of expansion of Semiconductor substrate, due to the thermal coefficient of expansion of the second film after processing
It is high temperature more than the thermal coefficient of expansion of Semiconductor substrate and above-mentioned processing, thus, during laser heat treatment, Semiconductor substrate and its back of the body
The second film both ends in face tend to tilt to the Semiconductor substrate back side, and the tilting of above-mentioned tilting trend and the first film is offset, because
And after cooling down, flat Semiconductor substrate, the first film and the second film can be obtained, and flat the first film is still located after release
In flat state, so as to make to obtain the high MEMS of movable member sensing sensitivity in a manner of low cost.
It is understandable to enable the above objects, features and advantages of the present invention to become apparent, below in conjunction with the accompanying drawings to the present invention
Specific embodiment be described in detail.
Fig. 1 to Fig. 7 is structural representation of the MEMS in the different production phases of one embodiment of the invention offer.Below
With reference to shown in Fig. 1 to Fig. 7, preparation method that MEMS is discussed in detail.
First, the sectional view of A-A straight lines along Fig. 1 shown in the top view and Fig. 2 shown in reference picture 1, there is provided partly lead
Body substrate, the Semiconductor substrate front have the first film 12, and the thermal coefficient of expansion of the first film 12 is more than described half
The thermal coefficient of expansion of conductor substrate.
In the present embodiment, Semiconductor substrate is silicon substrate 10 or SOI, and the material of the first film 12 thereon is, for example, silicon
Germanium, formed for example with furnace process, it is, for example, 300 DEG C~500 DEG C to form temperature.In other embodiments, the first film 12
Material can also be the metal such as copper or aluminium, formed using physical vapour deposition (PVD) under high temperature or chemical vapor deposition.This is first thin
Film 12 is subsequently used for being formed movable member, and in the present embodiment, the movable member is the movable sensitive film of both ends support, Qi Tashi
Apply in example, the movable member can also be the single armed beam of single-ended support.There is transistor, metal mutually to link in Semiconductor substrate front
Structure (not shown) etc., to be electrically insulated to the movable member, between the first film 12 and silicon substrate 10 or SOI, or first thin
Subregion between film 12 and metal interconnection structure has insulating barrier 11, and the insulating barrier 11 is subsequently used for forming support end, by
Covered, thus the region of insulating barrier 11 is employed in Fig. 1 shown in phantom by the first film 12 in insulating barrier 11.Insulating barrier 11
Material is, for example, silica or silicon nitride.
Due to for high temperature during above-mentioned deposition the first film 12, and the thermal coefficient of expansion of the first film 12 is more than semiconductor
The thermal coefficient of expansion of substrate, thus the stress deformation of the SiGe of the first film 12 is more than the stress deformation of the silicon of Semiconductor substrate,
The first film 12 pulls silicon semiconductor substrate, after cooling, as shown in Figure 3, it may appear that both ends are upturned (to Semiconductor substrate
Positive warpage) phenomenon.
To solve the above problems, then, shown in reference picture 4, continue to form the second film 13, ginseng at the Semiconductor substrate back side
Make its thermal coefficient of expansion more than the heat of the Semiconductor substrate according to laser heat treatment shown in Fig. 5, is carried out to second film 13
The coefficient of expansion.
Specifically, with initial reference to the Semiconductor substrate shown in Fig. 4, is overturn, make its back side upward, form on the back side
Two films 13, the material of second film 13 is, for example, SiGe or unformed silicon.SiGe is given birth to for example with furnace process or extension
Regular way is formed in silicon substrate 10 or the SOI back sides, and unformed silicon carries out Si ion implantation for example with to silicon substrate 10 or the SOI back sides
Formed.
Density becomes big after SiGe or unformed silicon absorb ultraviolet at high temperature, and the second film 13 ' after density becomes big (is joined
According to shown in Fig. 6) thermal coefficient of expansion become big, and more than the thermal coefficient of expansion of Semiconductor substrate.It is as shown in figure 5, above-mentioned ultraviolet sharp
Photothermal treatment is high temperature, with reference to shown in Fig. 6, because the thermal coefficient of expansion of the second film 13 ' is more than the thermal expansion of Semiconductor substrate
Coefficient, thus the stress deformation of the second film 13 ' is more than the stress deformation of the silicon of Semiconductor substrate, the second film 13 ' drawing silicon
Semiconductor substrate, both ends can tend to downsagging (to the back side warpage of Semiconductor substrate).
As can be seen that the warpage of the deformation tendency of the second film 13 ' obtained after above-mentioned processing and the first film 12 on the contrary,
Laser heat treatment thus is carried out using to the second film 13, can be offset with the warpage of the first film 12.After laser heat treatment, such as scheme
Shown in 6, need to only cool can obtain flat Semiconductor substrate, the film 13 ' of the first film 12 and second.
It should be noted that the property big based on ultraviolet line density change is absorbed under above-mentioned SiGe or unformed silicon high temperature, this
What is carried out in embodiment is that Ultra-Violet Laser is heat-treated, and in other embodiments, can also select it according to the property of the second film 13
The laser heat treatment of its wave band makes its density become big, and thermal coefficient of expansion becomes greatly to the thermal coefficient of expansion for being more than silicon substrate.
Research shows, is the film 13 of the first film 12 and second of SiGe for material, the second film 13 is entered
In capable Ultra-Violet Laser heat treatment, technological parameter is：Temperature is more than 1000 DEG C, wave-length coverage：100nm~400nm, energy are less than
2J/cm2, when the time is less than 1 μ s, the big degree of density change and the big degree of thermal coefficient of expansion change to the second film 13 can obtain non-
Warpage, flat the first film 12, the second film 13 ' and Semiconductor substrate.In addition, research shows, under above-mentioned technological parameter, with
The depth bounds that second film 13 closes on is that the temperature of the Semiconductor substrate in 10 μm is more than 100 DEG C, and depth bounds is 10 μm outer
Semiconductor substrate temperature be less than 100 DEG C, for the wafer (725 μm) of standard, the positive the first film 12 of Semiconductor substrate
Temperature be less than 50 DEG C, thus Ultra-Violet Laser influence of the heat treatment to Semiconductor substrate and its positive the first film 12 compared with
It is small, both will not be caused to damage.
Afterwards, shown in reference picture 7, after cooling, release is carried out to the first film 12 and forms it into movable member.
Specifically, shown in reference picture 7, after cooling, the Semiconductor substrate is overturn, makes it face-up, in the first film
Patterned first mask layer (not shown) is formed on 12, using patterned first mask layer as described in mask dry etching
The first film 12, form patterned the first film 12 '.Afterwards, on patterned the first film 12 ' and Semiconductor substrate
Patterned second mask layer (not shown) is formed, is served as a contrast using patterned second mask layer as semiconductor described in mask corrosion
Bottom, in the present embodiment, for example with the subregion in TMAH solution selective removal silicon substrate 10 or SOI, groove is formed, should
Groove serves as the cavity 20 of suspension the first film 12, in this way, being discharged to the first film 12, becomes movable member.
It is understood that in the present embodiment, the first film 12 of suspension is both ends support, thus for both ends support can
Dynamic sensitive thin film, in other embodiments, the first film 12 of above-mentioned suspension can also be etched and be supported for one end, you can dynamic component
For single armed beam.
It should be noted that in the present embodiment, cavity 20 is formed by etching silicon substrate 10 or SOI, in other embodiments,
There can also be sacrifice layer (not shown) in Semiconductor substrate, the first film 12 is formed on sacrifice layer, removes the sacrifice layer
The cavity 20 of suspension the first film 12 can also be formed, so realizes that the release to the first film 12 forms it into movable member.
The material of sacrifice layer can be silica, be removed for example with HF acid, and the material of sacrifice layer can also be agraphitic carbon, such as
Removed using ashing method.
Above-mentioned preparation method forms flat movable member, thus movable member sensing sensitivity is high, in addition, such scheme
In the second film 13 formation and make its thermal coefficient of expansion increase method cost it is relatively low, i.e., made in a manner of inexpensive
The high MEMS of movable member sensing sensitivity.
Although present disclosure is as above, the present invention is not limited to this.Any those skilled in the art, this is not being departed from
In the spirit and scope of invention, it can make various changes or modifications, therefore protection scope of the present invention should be with claim institute
The scope of restriction is defined.
Claims (13)
1. a kind of preparation method of MEMS, including：
Semiconductor substrate is provided, in Semiconductor substrate front deposition the first film, the thermal coefficient of expansion of the first film
More than the thermal coefficient of expansion of the Semiconductor substrate；
Characterized in that, continuing to form the second film at the Semiconductor substrate back side, laser heat treatment is carried out to second film
Its thermal coefficient of expansion is set to be more than the thermal coefficient of expansion of the Semiconductor substrate；
The thermal coefficient of expansion that laser heat treatment makes its thermal coefficient of expansion be more than the Semiconductor substrate is carried out to second film
The change of its density is set to realize greatly by carrying out laser heat treatment to second film；
After cooling, release is carried out to the first film and forms it into movable member.
2. preparation method according to claim 1, it is characterised in that the material of the Semiconductor substrate is silicon, described
The material of one film is SiGe, copper or aluminium.
3. preparation method according to claim 2, it is characterised in that the first film is formed using furnace process, temperature
It is 300 DEG C~500 DEG C to spend scope.
4. preparation method according to claim 1, it is characterised in that second film can absorb ultraviolet, and described
Density becomes big after two films absorb ultraviolet in laser heat treatment.
5. preparation method according to claim 4, it is characterised in that the material of second film is SiGe or unformed
Silicon.
6. preparation method according to claim 5, it is characterised in that to second film carry out laser heat treatment be
Ultra-Violet Laser is heat-treated.
7. preparation method according to claim 6, it is characterised in that the temperature of the Ultra-Violet Laser heat treatment is more than 1000
℃。
8. preparation method according to claim 6, it is characterised in that the wave-length coverage of Ultra-Violet Laser heat treatment is：
100nm~400nm.
9. preparation method according to claim 6, it is characterised in that the energy of the Ultra-Violet Laser heat treatment is less than 2J/
cm2。
10. preparation method according to claim 9, it is characterised in that the time of the Ultra-Violet Laser heat treatment is less than 1 μ
s。
11. preparation method according to claim 1, it is characterised in that the movable member is that single armed beam or both ends support
Movable sensitive film.
12. preparation method according to claim 1, it is characterised in that the Semiconductor substrate is silicon substrate or SOI, right
The first film release, which forms it into movable member, to be realized by the silicon substrate or SOI of erosion removal subregion.
13. preparation method according to claim 1, it is characterised in that there is sacrifice layer, to institute in the Semiconductor substrate
Stating the first film release and forming it into movable member is realized by removing the sacrifice layer.
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5183783A (en) * | 1990-12-28 | 1993-02-02 | Shin-Etsu Handotai Co., Ltd | Method for production of dielectric-separation substrate |
| US6756285B1 (en) * | 1999-02-10 | 2004-06-29 | Commissariat A L'energie Atomique | Multilayer structure with controlled internal stresses and making same |
| CN102024783A (en) * | 2009-09-22 | 2011-04-20 | 中芯国际集成电路制造(上海)有限公司 | Semiconductor element for use in interconnection process and manufacturing method thereof |
| CN102420176A (en) * | 2011-06-15 | 2012-04-18 | 上海华力微电子有限公司 | Method for improving warping of semiconductor wafer |
| CN102598243A (en) * | 2009-10-30 | 2012-07-18 | 索泰克公司 | Method for controlling the distribution of stresses in a semiconductor-on-insulator type structure and corresponding structure |
-
2014
- 2014-12-02 CN CN201410720429.8A patent/CN105712286B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5183783A (en) * | 1990-12-28 | 1993-02-02 | Shin-Etsu Handotai Co., Ltd | Method for production of dielectric-separation substrate |
| US6756285B1 (en) * | 1999-02-10 | 2004-06-29 | Commissariat A L'energie Atomique | Multilayer structure with controlled internal stresses and making same |
| CN102024783A (en) * | 2009-09-22 | 2011-04-20 | 中芯国际集成电路制造(上海)有限公司 | Semiconductor element for use in interconnection process and manufacturing method thereof |
| CN102598243A (en) * | 2009-10-30 | 2012-07-18 | 索泰克公司 | Method for controlling the distribution of stresses in a semiconductor-on-insulator type structure and corresponding structure |
| CN102420176A (en) * | 2011-06-15 | 2012-04-18 | 上海华力微电子有限公司 | Method for improving warping of semiconductor wafer |
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