My guess is that you do not understand what RAW is. RAW files are not images. Information is missing from them to form a complete image and RAW-conversion software interpolates (intelligently guesses) the missing data.
There is no such problem with a scanner since you have a complete image already. Therefore it makes NO sense for scanners to output RAW data like cameras do.
What you probably want is a high bit-depth to capture a more variations then JPEG files can contain. This helps when you are doing image adjustments (tone, contrast, curves, etc). In this case the scanner will usually produce a TIFF file, although other formats such as Cineon too.
The scanning software usually has a setting interface somewhere when it asks you for different settings such as DPI. Look for one that says bit-depth. If it says 24 bits-per-pixel (bpp) then that is equivalent to a JPEG. You can usually choose 36-bits which is similar to the color-depth found in RAW files (depending on the camera). On some scanners, there is also a 48-bit option which is beyond that.
You can scan to a bit-depth as high as you want BUT to make a difference, information has to be there. If you are scanning something that has only 6 bits of color-variations, then scanning at 36 vs 48 bits won't be of any use. The truth is that this relationship of color-depth from printers versus color-depth of digital cameras is an extremely complex subject better left for another discussion. Suffice to say that anything beyond 24-bits is probably overkill.