SATPC0033606 Tab 04 4 Spec sheet.pdf

Specifications for Procurement of UVLED Mask Aligner Tool for Patterning of Wafers Up To 150 mm Diameter

Scope:

NASA Glenn Research Center has need of a mask aligner tool for carrying out high-precision photolithographic patterning of semiconductor wafers including circular-shaped wafers of 150 mm in wafer diameter as well as semiconductor wafer pieces of irregular size and shape down to 1 cm x 1 cm square.

General Background:

The basic configuration, operation, and use of mask aligner tools is well known to those skilled in the art of semiconductor electronic device manufacture. In particular, a mask aligner tool is used to align a mask (a plate made of a transparent material such as glass or quartz with a user-desired microscopic opaque pattern on it) with an underlying semiconductor wafer (that is thin and flat and also contains a microscopic pattern) whose top surface has been coated with a very thin film sensitive to ultraviolet light. In order to accomplish alignment of the wafer pattern to the mask pattern, the user simultaneously views the wafer and mask pattern through microscopic optics that are a sub-system of the overall aligner tool. Using a highly precise alignment stage mechanism (sub-system), the user can manipulate tool controls that move the wafer position and rotation relative to the mask position until desired microscopic alignment of the mask pattern to the wafer pattern is achieved. Once satisfied with the alignment of the mask and wafer patterns, the user triggers the aligner’s exposure sub-system to provide a strong ultraviolet light exposure of the mask and underlying wafer at a desired wavelength and light intensity for a desired time.

In transparent mask regions the exposure light alters the photosensitive film properties (which is then developed after the wafer and film are removed from the aligner), whereas the underlying photosensitive film is not altered where opaque mask regions prevented light penetration. This general process is repeatedly used to define microscopic features during the fabrication of enabling semiconductor electronic devices.

Specifications:

The mask aligner system shall generally function as described in the above General Background section. However, NASA has many further technical requirements that are necessary for this tool to function adequately for the particular prototype semiconductor device development work that NASA is committed to successfully and safely accomplishing. Therefore, the mask aligner tool and associated sub-systems shall meet ALL technical and functional specifications listed below:

1. Masks: The mask aligner tool shall be delivered with all tooling and fixtures such that NASA-supplied masks of the following sizes can be readily/quickly loaded, used for microscopic photolithographic pattern exposure, and unloaded:

1.1. 127 ± 2 mm x 127 ± 2 mm mask size with mask thickness range up to 4.5 mm.

1.2. 178 ± 3 mm x 178 mm ± 3 mm mask size with mask thickness range up to 4.5 mm.

2. Microscopic Viewing Subsystem: The mask aligner tool shall facilitate microscopic optical viewing of the mask and underlying wafer simultaneously during the wafer-to-mask alignment process.

The microscopic viewing subsystem shall:

2.1. Have an included video system for the operator to view microscopic optical image of the wafer and mask in desired inspection regions while conducting the mask-to-wafer alignment process.

2.3.1. The video image shall be sufficient in size and clarity to enable the operator to execute substrate to mask alignment to standards of Specification 7.

2.2. Have focus adjustment controls that enable the user to properly adjust and attain good focus of the microscopic optical image. The optical focus-adjustment process shall not result in microscopically observable movement to the wafer or mask.

2.3. Facilitate high-magnification microscopic inspection of desired wafer & mask regions across the majority of a 150 mm diameter wafer surface area, wherein user controls with are provided for the user to select/navigate to specific wafer/mask regions for microscopic inspection of mask-feature to wafer-feature alignment marks including the following features:

2.3.1. Provide an independent control mechanism for the user to move the microscopic inspection region strictly in the lateral X direction (left-to-right with respect to the aligner operator) wherein microscope movement in the perpendicular lateral Y direction is mechanically de-coupled or inhibited.

2.3.2. Provide an independent control mechanism for the user to move the microscopic inspection region strictly in the lateral Y direction (front-to-back with respect to the aligner operator) wherein microscope movement in the perpendicular lateral X direction is mechanically de-coupled or inhibited.

2.3.3. Provide for all lateral movement of the microscopic inspection region as described in 2.3.1 and 2.3.2 above without any microscopically observable movement of the wafer relative to the mask.

2.3.4. Provide for all lateral direction movement of the microscopic inspection area described in 2.3.1 through 2.3.3 above without need for operator-adjustment of the focus controls described in 2.2 to keep the mask pattern in focus.

3. Ultraviolet Light Emitting Diode (UVLED) Light Exposure Subsystem: The mask aligner tool shall have an Ultraviolet (UV) Light Emitting Diode (LED) based Exposure Subsystem to accomplish highly uniform user-adjustable electronically controlled light exposures of the wafer top surface by “i-line” 365nm ± 5nm ultraviolet wavelength generated by a matrix of solid-state UV LEDs at intensities sufficient to permit high-resolution patterning of standard photoresist.

The UVLED Light Exposure Subsystem shall:

3.1. Have user-settable electronic timing circuit for starting and stopping exposures.

3.1.1. The user shall be able to set the electronically controlled exposure time to any value desired over at least the range from 1 second to 3600 seconds.

3.1.2 The user shall be able to program the aligner tool to electronically repeat a desired number of sequential light exposure cycles of fixed exposure time.

3.2. Have user-settable ultraviolet “i-line” 365nm ± 5 nm wavelength exposure intensity that is constant to within 10% and over at least the range of 3 mW/cm2 to 30 mW/cm2 at the wafer surface.

3.3. Have ultraviolet light divergence beam angle of less than 2.0 degrees.

3.4. UV expose the wafer surface in a manner such that the wafer substrate surface temperature does not increase by more than 1 °C from its pre-exposure temperature near 25 °C (room temperature) throughout a 3600 second exposure time.

3.5. Provide for the UVLED light source, mask, and wafer being UV-light exposed to reside completely and safely within a fully enclosed outer tool casing structure that prevents ultraviolet light (potentially harmful to human eyes) from exiting the tool casing structure enclosure when:

3.5.1. The UV light source is powered on.

3.5.2. The wafer is being UV-light exposed.

This fully enclosed outer casing structure shall also prevent microscopic contamination particles present in the laboratory room air environment (such as dust and human hair and skin cell particles) from adversely reaching the mask or wafer during the alignment and exposure process. Furthermore, this

3.6. Have a UV exposure intensity variation of less than 5% across the entire 150mm diameter wafer area during wafer exposure.

3.7. Include all power supplies, sensors, circuits and controls necessary to operate the UVLED light source and carry out wafer exposures according to all specifications in this Section 3.

3.8. Carry out UV light exposures, as the user selects via controls provided on the aligner tool, in at least the following modes listed below:

3.8.1: Contact mode: The top wafer surface in physical contact with the bottom surface of the mask, and the physical contact force/pressure shall be adjustable by the user (see also Specification 5.4).

3.8.2: Proximity mode: The top wafer surface in close proximity to within 10 micrometers of the bottom surface of the mask but not in physical contact, and the proximity separation distance shall be adjustable by the user (see also Specification 5.4).

3.9. Not require replacement/refurbishment/changeout of the UVLED light source for at least 5 years of normal tool operations.

4. Wafer Size and Shape: The mask aligner tool shall operate and perform alignment and exposure functions according to all other specifications in this document for all wafers less than 1 mm in thickness with thickness non-uniformity of up to 0.1% and free of enclosed voids falling within lateral sizes and shapes within area dimensions ranging from 150 mm diameter circular lateral shape at largest down to 50 mm x 50 mm square lateral shape at smallest.

5. Wafer to Mask Alignment Subsystem: The mask aligner tool shall have a mechanism that enables the operator to precisely position (align) a microscopic wafer pattern to a microscopic mask pattern prior to carrying out desired UV exposure of the mask and wafer surfaces. The wafer to mask alignment subsystem shall:

5.1. Provide wafer holder hardware with suitable arrangement of vacuum holes employed for firmly holding the wafer stationary on the chuck surface without slippage during the alignment and exposure procedure. The wafer holder hardware shall at a minimum holding the following wafers size and shapes during mask alignment and UV exposure:

5.1.2.1. 150 ± 3 mm diameter circular wafer shape.

5.1.2.2. 100 ± 2 mm diameter circular wafer shape.

5.1.2.5. 100 mm x 100 mm square wafer shape.

5.2. Have three high precision alignment positioner controls to enable adjustment of the lateral translation (X and Y direction) lateral rotation position (angle theta) of the wafer (held on mechanical wafer holder as described in 5.1 above) relative to the mask along the lateral plane parallel to the wafer and mask surfaces.

5.2.1. One alignment positioner control shall independent of the other positioner controls adjust to less than 0.5 micrometer resolution the lateral position of the wafer in the Y direction that is front-to-back with respect to the operator without inducing movement of the wafer in the perpendicular lateral left-to-right direction to the operator nor in the vertical direction normal to the mask and wafer surfaces.

The Y direction wafer/chuck translation travel distance enabled by this positioner shall exceed 6 mm.

5.2.2. One alignment positioner control shall independent of the other positioner controls adjust to less than 0.5 micrometer resolution the lateral position of the wafer in the X direction that is left-to-right with respect to the operator without inducing movement of the wafer in the perpendicular lateral front-to-back direction to the operator nor in the vertical direction normal to the mask and wafer surfaces. The X direction wafer/chuck translation travel distance enabled by this positioner shall exceed 6 mm.

5.2.3. One alignment positioner control shall independent of the other positioner controls laterally rotate the wafer in the horizontal plane parallel to the mask surface with a vertical axis of rotation running through within 1 mm of the geometric center of the wafer chuck to adjustment theta angle resolution less than

0.001 of a degree. The theta angle adjustment travel by this positioner shall exceed 3 degrees.

5.4. Have vertical Z direction control for the operator to repeatably change/adjust the vertical physical separation distance between the wafer top surface plane and bottom mask plane. For the special case defined as “contact” in which the wafer top surface is Z-positioned positioned to be in uniform physical contact with the mask bottom surface, the physical separation distance is zero micrometers.

5.4.1. The Z control shall facilitate small, adjustable, and repeatable separation distance in increments no larger than 1 micrometer and ranging over 10 micrometers.

5.4.2. Adjustments of Z vertical separation distance shall not impose lateral X and Y movement/repositioning of the wafer relative to the mask of in excess of 0.5 micrometers.

5.4.3. In “contact” mode, the tool shall have a contact force/pressure indicator and adjustment control that permits the user to measure and adjust the force/pressure of contact between the wafer and the mask.

5.5. The aligner tool shall properly function in accordance with all other specifications in this document over the entire range of wafer thicknesses described in Specification 4 above.

6. Performance: The mask alignment tool shall reproducibly achieve an alignment tolerance of

1.0 um or less and a minimum pattern feature size of 1.0 um or less over the majority of a patterned 150 mm diameter silicon wafer.

7. Available Utilities: The mask aligner tool shall operate in conformance of all specifications using the following utilities provided by the Government to the specific intended location of aligner tool installation:

7.1. 120 VAC 60 Hz electrical outlets totaling no more than 250 W total electrical power.

7.2. 100 PSI Compressed nitrogen supply.

7.3. -12 PSI Vacuum supply.

8. Physical Size: The mask aligner tool shall not exceed dimensions 1 m in height x 1 m in width x 1 m in depth and shall not exceed an overall weight of 100 kg.

9. Operator’s Manual: An operator’s manual for the mask alignment system written in the English language shall be electronically provided to NASA in PDF format. This manual shall adequately diagram and describe all standard controls and standard operating procedures and periodic maintenance and calibrations needed for a user to use the tool to perform normal intended mask alignment operations within technical specifications over the course of multiple years of use, including at least:

9.1. System power-on and preparation for use procedures.

9.2. Mask loading and unloading.

9.3. Wafer chuck loading and unloading.

9.4. Wafer loading and unloading.

9.6. Microscopic imaging system, including illumination, focusing, and video display.

9.7. Wafer positioning relative to the mask prior to UV light exposure.

9.8. Wafer exposure modes and controls.

9.9. UV light exposure preparations and procedures.

9.10. Potential hazards, warnings, precautions, related to operator and laboratory safety, including descriptions of system safety interlocks.

9.11. Parts, replacement instructions, and recommended calibration/replacement schedules and procedures that the user is expected to maintain, replace, and calibrate/replace periodically.

9.12. Photographs and/or drawing of the system showing all major subsystems and user displays and controls.

9.13. Installation instructions and procedures.

10. Delivery: The contractor shall deliver the mask alignment system in conformance with above Specifications 1 through 9 to the NASA Glenn Research Center, Building 77, Room 304, 21000 Brookpark Road, Cleveland, OH 44135 USA. The mask alignment system shall be delivered no later than six weeks following the date of contract issuance.

11. Acceptance Testing: Using a NASA-supplied wafer sample and mask, NASA shall confirm that the aligner performs to the specifications (particularly Specification 6) by aligning, exposing, and developing a test photolithographic pattern on a silicon wafer.

12. Training of Users at NASA: Upon the completion of installation, the contractor shall train least three key NASA Glenn technical personnel (contractors and/or civil servants) to proficiently operate the mask aligner tool by themselves using the installed system at NASA Glenn Research Center. This training can be conducted virtually at a time mutually agreed to by NASA and the contractor after the mask aligner has been delivered.

Bidding Requirement for Descriptive Technical Literature:

In order for the Government to effectively conduct its technical evaluation of bids to verify that bidders can acceptably meet the stringent and critical technical specifications/requirements outlined for this procurement, each bidder shall supply as part of its procurement bid package an electronic copy (PDF file format) of the proposed aligner tool’s Operator’s Manual written in the English language in conformance with Specification 9. Failure to submit required sufficiently descriptive literature so as to facilitate technical evaluation by the Government will be grounds for unfavorable dismissal of bid.