Micron Technology Incorporated

Round Rock Research, LLC

Cista System Corp.

Aptina Imaging Corporation

Jingyi Bai

Gurtej S Sandhu

Zhiping Yin

Shuang Meng

Luan C Tran

John K Lee

D Mark Durcan

Mirzafer K Abatchev

Paul A Morgan

William T Rericha

Ramakanth Alapati

Puneet Sharma

Sheron Honarkhah

Max F Hineman

Shane J Trapp

Tony Schrock

Daniel A Steckert

Weimin Li

Hirofumi Komori

William Budge

Sergey Velichko

An image sensor including at least one pixel for collecting charge in its photodiode is provided. The image sensor comprises: a substrate having a first surface on a front side and a second surface on a back side, a photodetector formed in the silicon substrate and having a light-receiving surface on the second surface, and a first layer with positive charges disposed on the second surface, the first layer being configured to form an electron accumulation region at the light-receiving surface of the photodetector for suppressing a dark current at a back side interface of the image sensor. A method for fabricating an image sensor including a first layer with positive charges is also provided.

Back side illuminated CMOS image sensor arrays

A global shutter pixel cell includes a serially connected anti-blooming (AB) transistor, storage gate (SG) transistor and transfer (TX) transistor. The serially connected transistors are coupled between a voltage supply and a floating diffusion (FD) region. A terminal of a photodiode (PD) is connected between respective terminals of the AB and the SG transistors; and a terminal of a storage node (SN) diode is connected between respective terminals of the SG and the TX transistors. A portion of the PD region is extended under the SN region, so that the PD region shields the SN region from stray photons. Furthermore, a metallic layer, disposed above the SN region, is extended downwardly toward the SN region, so that the metallic layer shields the SN region from stray photons. Moreover, a top surface of the metallic layer is coated with an anti-reflective layer.

Global shutter pixel with improved efficiency

A method of high aspect ratio contact etching a substantially vertical contact hole in an oxide layer using a hard photoresist mask is described. The oxide layer is deposited on an underlying substrate. A plasma etching gas is formed from a carbon source gas. Dopants are mixed into the gas. The doped plasma etching gas etches a substantially vertical contact hole through the oxide layer by doping carbon chain polymers formed along the sidewalls of the contact holes during the etching process into a conductive state. The conductive state of the carbon chain polymers reduces the charge buildup along sidewalls to prevent twisting of the contact holes by bleeding off the charge and ensuring proper alignment with active area landing regions. The etching stops at the underlying substrate.

Method to reduce charge buildup during high aspect ratio contact etch

An integrated circuit having differently-sized features wherein the smaller features have a pitch multiplied relationship with the larger features, which are of such size as to be formed by conventional lithography.

Integrated circuit having pitch reduced patterns relative to photoithography features

Differently-sized features of an integrated circuit are formed by etching a substrate using a mask which is formed by combining two separately formed patterns. Pitch multiplication is used to form the relatively small features of the first pattern and conventional photolithography used to form the relatively large features of the second pattern. Pitch multiplication is accomplished by patterning a photoresist and then etching that pattern into an amorphous carbon layer. Sidewall spacers are then formed on the sidewalls of the amorphous carbon. The amorphous carbon is removed, leaving behind the sidewall spacers, which define the first mask pattern. A bottom anti-reflective coating (BARC) is then deposited around the spacers to form a planar surface and a photoresist layer is formed over the BARC. The photoresist is next patterned by conventional photolithography to form the second pattern, which is then is transferred to the BARC. The combined pattern made out by the first pattern and the second pattern is transferred to an underlying amorphous silicon layer and the pattern is subjected to a carbon strip to remove BARC and photoresist material. The combined pattern is then transferred to the silicon oxide layer and then to an amorphous carbon mask layer. The combined mask pattern, having features of difference sizes, is then etched into the underlying substrate through the amorphous carbon hard mask layer.

Pitch reduced patterns relative to photolithography features

A photo acid generator (PAG) or an acid is used to reduce resist scumming and footing. Diffusion of acid from photoresist into neighbors causes a decreased acid level, and thus causes resist scumming. An increased acid layer beneath the resist prevents acid diffusion. In one embodiment, the increased acid layer is a layer of spun-on acid or PAG dissolved in aqueous solution. In another embodiment, the increased acid layer is a hard mask material with a PAG or an acid mixed into the material. The high acid content inhibits the diffusion of acid from the photoresist into neighboring layers, and thus substantially reduces photoresist scumming and footing.

Prevention of photoresist scumming

Pitch multiplication is performed using a two step process to deposit spacer material on mandrels. The precursors of the first step react minimally with the mandrels, forming a barrier layer against chemical reactions for the deposition process of the second step, which uses precursors more reactive with the mandrels. Where the mandrels are formed of amorphous carbon and the spacer material is silicon oxide, the silicon oxide is first deposited by a plasma enhanced deposition process and then by a thermal chemical vapor deposition process. Oxygen gas and plasma-enhanced tetraethylorthosilicate (TEOS) are used as reactants in the plasma enhanced process, while ozone and TEOS are used as reactants in the thermal chemical vapor deposition process. The oxygen gas is less reactive with the amorphous carbon than ozone, thereby minimizing deformation of the mandrels caused by oxidation of the amorphous carbon.

Multiple deposition for integration of spacers in pitch multiplication process

Differently-sized features of an integrated circuit are formed by etching a substrate using a mask which is formed by combining two separately formed patterns. Pitch multiplication is used to form the relatively small features of the first pattern. Pitch multiplication is accomplished by patterning an amorphous carbon layer. Sidewall spacers are then formed on the amorphous carbon sidewalls which are then removed; the sidewall spacers defining the first mask pattern. A bottom anti-reflective coating (BARC) is then deposited to form a planar surface and a photoresist layer is formed over the BARC. The photoresist is next patterned by conventional photolithography to form the second pattern, which is transferred to the BARC. The combined pattern is transferred to an underlying amorphous silicon layer. The combined pattern is then transferred to the silicon oxide layer and then to an amorphous carbon mask layer. The combined mask pattern, is then etched into the underlying substrate.

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San Jose, CA, United States of America

Jingyi Bai