A process to control diaphragm thickness with a provision for back to front alignment in the fabrication of polysilicon piezoresistive pressure sensor

Akhtar, Jamil; Pant, B. D.; Deshwal, V.P.; Joshi, B. C.

doi:10.1108/02602280310496827

Cited by 8 publications

(4 citation statements)

References 8 publications

(11 reference statements)

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“…The use of surfactant in a TMAH solution [20] was avoided in order to rule out any contamination to biological activities on the cantilever surface. Through holes within the wafer were used for alignment purposes [28].…”

Section: Microfabrication Stepsmentioning

confidence: 99%

A novel technique for microfabrication of ultra-thin affinity cantilevers for characterization with an AFM

Joshi¹,

Rao

Mukherji

2010

J. Micromech. Microeng.

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A novel, low-cost microfabrication technique for ultra-thin affinity cantilevers to be characterized using an atomic force microscope (AFM) has been demonstrated. Compared to its counterparts reported in the literature, it does not involve a double-sided aligner or deep reactive ion etching (DRIE). Such a microfabrication technique incorporates features like elimination of stiction during the wet release of cantilevers thereby increasing the process yield. It also eliminates the need for laser dicing and allows processing of a large number of cantilevers simultaneously for surface functionalization. Uses of these cantilevers for estimation of the mechanical properties of thin films as well as biosensor applications are demonstrated.

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Section: Microfabrication Stepsmentioning

confidence: 99%

A novel technique for microfabrication of ultra-thin affinity cantilevers for characterization with an AFM

Joshi¹,

Rao

Mukherji

2010

J. Micromech. Microeng.

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“…A double‐sided mask aligning system is one solution, which is not cost effective. A novel and cost effective procedure has been used for this purpose (Akhtar et al , 2003b). The method is also useful to control the diaphragm thickness in addition to provide facility for back to front alignment.…”

Section: Fabrication Processmentioning

confidence: 99%

A wet‐etch method with improved yield for realizing polysilicon resistors in batch fabrication of MEMS pressure sensor

Singh

Gupta²,

Azam³

et al. 2009

Sensor Review

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Purpose-The purpose of this paper is to present a selective wet-etching method of boron doped low-pressure chemical vapour deposition (LPCVD) polysilicon film for the realization of piezoresistors over the bulk micromachined diaphragm of (100) silicon with improved yield and uniformity. Design/methodology/approach-The method introduces discretization of the LPCVD polysilicon film using prior etching for the grid thus dividing each chip on the entire wafer. The selective etching of polysilicon for realizing of piezoresistors is limited to each chip area with individual boundaries. Findings-The method provides a uniform etching on the entire silicon wafer irrespective of its size and leads to economize the fabrication process in a batch production environment with improved yield. Research limitations/implications-The method introduces one extra process step of photolithography and subsequent etching for discretizing the polysilicon film. Practical implications-The method is useful to enhance yield while defining metal lines for contact purposes on fabricated electronic structures using microelectronics. Stress developed in LPCVD polysilicon can be removed using proposed approach of discretization of polysilicon film. Originality/value-The work is an outcome of regular fabrication work using conventional approaches in an R&D environment. The proposed method replaces the costly reactive ion etching techniques with stable reproducibility and ease in its implementation.

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“…The discovery of piezoresistivity in silicon and germanium (Smith, 1954) and subsequent development for anisotropic etching of crystalline silicon (Bean, 1978; Petersen, 1982) has enabled the production of semiconductor‐based sensors (Hashimoto, 1999; Pryputniewicz et al , 2000). Advances in microfabrication technology have led to the development of bulk‐micromachined (Mosser et al , 1991; Akhtar et al , 2003; Ahmad et al , 2003) and surface‐micromachined (Guckel, 1991) sensors available today. The first micromechanical sensor was the piezoresistive pressure sensor, which was developed at Bell Labs in 1960.…”

Section: Introductionmentioning

confidence: 99%

Fabrication of a membrane type double cavity vacuum‐sealed micro sensor for absolute pressure based on front‐side lateral etching technology

Rathore

Akhtar

2011

Sensor Review

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PurposeThe purpose of this paper is to describe the fabrication of a miniaturized membrane type double cavity vacuum‐sealed micro sensor for absolute pressure using front‐side lateral etching technology.Design/methodology/approachPotassium hydroxide‐based anisotropic etching of single crystal silicon is used to realize the cavities under the membrane type diaphragms through channels on the sides. The diaphragms consist of composite layers of plasma‐enhanced chemical vapour deposition (PECVD) of silicon nitride and silicon dioxide. PECVD of silicon dioxide is done for sealing the channels and the cavity in vacuum. Boron thermal diffusion in low‐pressure chemical vapour deposition of polysilicon layer over the membrane is done for realizing resistors. The fabricated device uses Wheatstone half bridge circuit to read the variation of resistance with respect to an applied pressure.FindingsA double cavity vacuum‐sealed absolute pressure micro sensor has been fabricated successfully using front‐side lateral etching technology and has been measured for pressure range of 0‐0.45 MPa. The measured pressure sensitivity of two pressure sensors is 9.28 and 10.44 mV/MPa.Originality/valueThe paper shows that front‐side lateral etching technology is feasible in the fabrication of small vacuum‐sealed cavities and absolute pressure sensors.

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A process to control diaphragm thickness with a provision for back to front alignment in the fabrication of polysilicon piezoresistive pressure sensor

Cited by 8 publications

References 8 publications

A novel technique for microfabrication of ultra-thin affinity cantilevers for characterization with an AFM

A novel technique for microfabrication of ultra-thin affinity cantilevers for characterization with an AFM

A wet‐etch method with improved yield for realizing polysilicon resistors in batch fabrication of MEMS pressure sensor

Fabrication of a membrane type double cavity vacuum‐sealed micro sensor for absolute pressure based on front‐side lateral etching technology

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