Deciding to use a period versus a semicolon before "Is that correct?" and expecting your reader to distinguish that they mean something different is an exercise in extreme subtlety. This distinction has been pushed around out there for a long time.
...You testified that he arrived at 9:00; is that correct? -- meaning is it correct that you testified to this?
...You testified that he arrived at 9:00. Is that correct? -- meaning is it correct that he arrived at 9:00?
I am just not sure that anyone looks at the period and says, "Ah. It means X," and then looks at the semicolon and says, "Ah. It means Y." That is, I just am not sure that this distinction is "obvious" from the punctuation. You certainly may use this difference if you want, though it is not really a "rule" that you are going to find in any standard English reference.
And, by the way, if the answer is "Yes," then the question just wasn't effective anyway.
Where a period instead of a semicolon really should be used is the situation where you have a very long question with a bunch of "facts" in it. Then a period and probably even a paragraph before "Is that correct?" is the best punctuation.
Happy punctuating!
Margie